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Biomedical subjects

M Mariani

Publications and source records attributed to M Mariani.

At least 145 records · Page 8Linked to original sources
PubMed1994

Growth-inhibitory properties of novel anthracyclines in human leukemic cell lines expressing either Pgp-MDR or at-MDR.

The objective of the experiments reported in this paper was the identification of promising anthracycline analogs on the basis of lack of cross-resistance against tumor cells presenting either P-glycoprotein multidrug resistance (Pgp-MDR) or the altered topoisomerase multidrug resistant (at-MDR) phenotype. Differently modified anthracycline analogs known to be active against MDR cells were assayed in vitro against CEM human leukemic cells, and the sublines CEM/VLB100 and CEM/VM-1 exhibiting respectively the Pgp-MDR and the at-MDR phenotype. Two classes of molecules, in which the -NH2 group in C-3' position is substituted with a morpholino, methoxymorpholino (morpholinyl-anthracycline), or an alkylating moiety, present equivalent efficacy in the drug-sensitive and the two drug-resistant sublines. These results indicate that such molecules may exert their cytotoxic effect through a mode of action different from that of "classical" anthracyclines and is not mediated through topoisomerase II inhibition. Both molecules represent novel concepts in the field of new anthracyclines derivatives.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Recombinant proteins L and LG. Two new tools for purification of murine antibody fragments.

Several bacterial cell wall proteins, like proteins A and G, with valuable affinity for immunoglobulins have been discovered and are currently employed in immunological techniques. In 1988, protein L, a bacterial cell wall protein with Ig-binding capacity, was isolated from the anaerobic bacterial species Peptostreptococcus magnus. Binding data with immunoglobulin fragments suggested that protein L could selectively bind the variable region of human kappa light chains. More recently a recombinant LG fusion protein was expressed in E. coli containing four repeated Ig-binding domains of protein L (fragment B1-4) and two IgG Fc-binding protein G domains (fragment CDC). Recombinant L and LG proteins were tested in the purification of murine monoclonal IgG and their fragments. After affinity-constant evaluation in different buffer systems, high-pressure affinity-chromatography columns were prepared by coupling the proteins to Affi-prep 10 resin and tested with eight different murine monoclonal antibodies and their fragments of various isotypes. Affinity-chromatography experiments confirming radioimmunoassay results showed 75% fragment-binding capacity of protein L and 100% of protein LG. These results evidenced protein LG as the most powerful Ig-binding tool so far described. Therefore, application of these proteins may be suggested in the purification of murine immunoglobulins and their fragments, including the engineered ones.

Animals↗
PubMed1994

Biosensor analysis of antigen-antibody interactions as a priority step in the generation of monoclonal bispecific antibodies.

A biosensor system aimed at real-time measuring molecular interactions among label-free reactants has been used for a comparative analysis of the binding features (i.e., association-dissociation rates and affinity constants) as well as epitope mapping between bivalent monoclonal antibodies and the derived monovalent bispecific monoclonal antibody. The results show that observed different affinities between parental and derived bispecific antibodies concern the association rate constant, whereas the dissociation rate constants are unaltered. The apparent affinity-constant values determined by solid-phase radioimmunoassay yielded figures almost overlapping with those obtained with the biosensor instrument. The results of the present work indicate that the biosensor system has gained a key role not only as a tool for the study of antigen-antibody interactions, but also for setting up the reference parameters for the selection of the best candidates in the generation of bispecific monoclonal antibodies.

Antibodies, Monoclonal↗
PubMed1994

Modulation of melatonin secretion by acetyl-L-carnitine in adult and old rats.

Modification of melatonin synthesis and release by acetyl-L-carnitine (ALC) was studied in adult (2 month old) and old (24-month-old) male Sprague Dawley rats. When ALC was injected at 1500 into adult rats at doses of 10, 30, or 90 mg/kg, there was a remarkable increase in their pineal and serum melatonin 1 hr later. However, using the same experimental protocol acute ALC administration in old rats did not modify pineal and serum melatonin levels. ALC administered in the same dose range induced a significant increase in pineal and serum melatonin in adult rats treated at 0100 h following exposure of 30 min to bright, white light to suppress endogenous melatonin. In the same conditions, in old rats, only the higher dose (90 mg/kg) caused any noteworthy increase in melatonin pineal content while lower doses were uneffective both on serum and pineal melatonin levels. It is known that ALC affects fatty acid transport in the cells, modulates CoA, modifies neuronal transmission and reduces lipofuscin accumulation which is related to lipid peroxidation. The action of ALC on melatonin synthesis could be the result of a modulation of the neuronal transmission related to circadian pineal endocrine activity. Moreover, since both ALC and melatonin exert remarkable scavenger activity, it is possible to suppose that ALC effects in reversing certain aging processing may be due to its ability to promote melatonin production.

Acetylcarnitine↗
PubMed1994

Effect of ischemia and reperfusion on cardiac ryanodine receptors--sarcoplasmic reticulum Ca2+ channels.

We investigated the effect of ischemia and reperfusion on the cardiac ryanodine receptor, which corresponds to the sarcoplasmic reticulum Ca2+ channel. Isolated working rat hearts were subjected to 10 to 30 minutes of global ischemia, followed or not by reperfusion. Ischemia produced significant reduction in the density of high-affinity 3H-ryanodine binding sites, determined either in whole-heart homogenate (Bmax, 220 +/- 22, 203 +/- 12, and 228 +/- 14 fmol/mg protein after 10, 20, and 30 minutes of ischemia versus 298 +/- 18 fmol/mg protein in the control condition; P < .01) or in a fraction enriched in sarcoplasmic reticulum (Bmax, 1.08 +/- 0.15 pmol/mg protein after 20 minutes of ischemia versus 1.69 +/- 0.08 pmol/mg protein in the control condition; P < .01). The Kd (1.5 +/- 0.1 nmol/L) and the Ca2+ dependence of high-affinity 3H-ryanodine binding were not affected by ischemia. The density of low-affinity 3H-ryanodine binding sites was also reduced after 20 minutes of ischemia (14.0 +/- 2.3 versus 34.0 +/- 8.2 pmol/mg protein in the sarcoplasmic reticulum fraction, P < .05), without significant changes in Kd (4.7 +/- 1.2 versus 2.4 +/- 1.0 mumol/L). All these changes persisted after 20 minutes of reperfusion. Analysis of tissue fractions showed that 55% of the ryanodine binding sites were retained in the pellet of a low-speed centrifugation ("nuclear pellet") and that the effects of ischemia concerned only the receptors released in the supernatant ("postnuclear supernatant"). In parallel experiments, we evaluated the effect of ryanodine on oxalate-supported Ca2+ uptake, which represents sarcoplasmic reticulum Ca2+ uptake. As expected, we found that high concentrations of ryanodine stimulated Ca2+ uptake, owing to channel blockade. The response to 900 mumol/L ryanodine was slightly reduced in crude homogenate and significantly reduced in postnuclear supernatant obtained from ischemic hearts. In conclusion, the number of ryanodine receptors is reduced after ischemia; this effect concerns a subpopulation of the receptors, persists after reperfusion, and might contribute to modify sarcoplasmic reticulum function.

Animals↗
PubMed1994

[Role of transesophageal echocardiography in mitral valve repair].

This study was designed to prove the utility of intraoperative echocardiography in the mitral valve repair, that offers many advantages over valve replacement. We have assessed 21 consecutive patients, 12 with mitral incompetence and 9 with mitral stenosis, undergoing mitral valve surgery over a period of 6 months. Preoperative transthoracic and intraoperative transesophageal or epicardial echocardiography were performed in all patients. We have assessed, before and after repair, the valve morphology, the presence and the severity of mitral regurgitation, the pulmonary venous flow, the presence of left ventricular outflow tract obstruction. The intraoperative echocardiographic examination revealed a successful mitral repair in all patients except one in whom, for the persistence of severe mitral regurgitation after repair, valve replacement was performed. In none patient systolic anterior motion of mitral apparatus was observed. Intraoperative echocardiography seems to be a useful technique to assess the adequacy of mitral valve repair before chest closure and, in the case of failure, the need for further surgery (valve reconstruction or replacement).

Adult↗
PubMed1994

[Late ventricular potentials and acute ischemia: study during percutaneous transluminal coronary angioplasty].

In order to assess if acute ischemia induces ventricular late potentials (VLP), we have studied 35 patients during coronary angioplasty (PTCA), 15 (Group A) with previous myocardial infarction, 20 (Group B) without. VLP detection was performed by standard technique (in the time domain, with Simson algorithm, on 200 beats, using a 25 Hz filter) before, during and 24 hours after PTCA. This procedure was performed on: anterior descending artery (19 cases), circumflex artery (9 cases), right coronary artery (11 cases); four patients had PTCA on two vessels; in Group A patients, PTCA was performed in vessels related to the previous myocardial infarction. VLP were defined as present when at least two of three standard criteria of positivity were detected (QRSD > 115 ms, RMS40 < 25 microV, LPD > 32 ms). In all patients also left ventricular ejection fraction, end diastolic pressure, regional kinesis and amount of myocardium at risk (as measured by the "Duke University jeopardy score") had been assessed. Furthermore, the total and mean inflation time and the degree of induced acute ischemia were also considered. The following results were obtained: no patient had VLP at basal conditions, during PTCA in all patients of both groups we observed a significant prolongation of QRSD but only Group A patients developed VLP, in 56% of cases versus none of Group B. This event was transient: in fact, 24 hours after the procedure VLP were no more present. The two groups did not differ as regards to the values of all the other anatomic and functional above mentioned parameters. Probably the acute ischemia cannot evocate VLP by itself, but this "trigger" needs also a particular substrate with anatomical and functional abnormalities due to a previous myocardial infarction. Further investigations and long follow-up studies are requested to assess if these data could account for the presence of ventricular tachyarrhythmias in patients with acute coronary ischemia and previous myocardial infarction.

Acute Disease↗
PubMed1993

A tightly membrane-associated subpopulation of spectrin is 3H-palmitoylated.

A tightly membrane-associated form of spectrin (TMA-spectrin) was labeled when human red blood cells were incubated with [3H]palmitic acid. About 90% of spectrin was not fatty acid-acylated and was extracted from membranes by low salt buffers. The 3H-palmitoylated TMA-spectrin, however, resisted low and even high salt extraction and remained associated with inside-out vesicles that were generated in the process of spectrin-actin extraction from membranes. TMA-spectrin was preferentially extracted from KCl-stripped vesicles by 5 M urea at low ionic strength. TMA-spectrin was purified by gel filtration and by ion exchange chromatography in the presence of urea and a non-ionic detergent. Purified TMA-spectrin was 3H-palmitoylated exclusively in the beta subunit to 0.28 mol/mol after a 12-h incubation of red cells. The labeled palmitate may be bound as an ester or thioester, since hydroxylamine (1 M, pH 7.5) released the label completely. Peptide maps of 3H-palmitoylated TMA-spectrin showed three or two labeled peptides from the beta subunit, when generated by V8 protease and trypsin, respectively. Two types of antibodies to spectrin reacted with purified TMA-spectrin, and TMA-spectrin contained the same antigenic peptides as low salt-extractable spectrin. Rabbit anti-ankyrin antibodies did not bind to TMA-spectrin. The substoichiometric incorporation of [3H]palmitic acid into TMA-spectrin could result from the slow turnover of endogenously bound fatty acids. Generation of the tightly membrane-associated and 3H-palmitoylated subpopulation of spectrin cannot be due to entrapment of an unmodified residual fraction of spectrin in right-side-out vesicles. Instead, the data suggest the existence of a subpopulation of spectrin molecules that undergo a covalent fatty acid modification and thereby alter their binding properties. This may offer a new, metabolically dependent mechanism for dynamic interactions between spectrin and the membrane lipid bilayer.

Electrophoresis, Polyacrylamide Gel↗
PubMed1993

Real-time kinetic analysis applied to the production of bispecific monoclonal antibodies for radioimmunodetection of cancer.

An automated biosensor system designed for measuring molecular interactions in real-time and without labelling of the reactants has been used to evaluate the association/dissociation rate and affinity constants of bivalent monoclonal antibodies and a monovalent bispecific monoclonal antibody. Observed differences in affinity between parental and bispecific antibody produced were related to the association rate constants, since the dissociation rate constants were in the same range. Values were also closely related to radioimmunochemical data. These results indicate that the biosensor system, besides presenting several advantages for characterizing antigen-antibody interaction, is valuable for selecting monoclonal antibodies with properties which might be useful in the development of bispecific monoclonal antibodies.

Antibodies, Bispecific↗
PubMed1993

[Pharmacological combinations in the treatment of benign prostatic hypertrophy].

In the development of the obstructive symptomatology of benign prostatic hypertrophy (BPH), two components may be identified, mechanical and dynamic. In the mechanical component, the interaction of a stromal and a epithelial compartment determines prostatic mass growth. The dynamic component involves smooth muscle tone in the prostate and urethra. The consideration that prostatic disease is not only epithelial in origin, but also stromal, leads to the association of an antiandrogen (which acts on the epithelial component) and an antiestrogen (active on the stromal component) in the medical therapy of BPH. In 1985 we carried out a randomized study on 256 BPH patients treated with Cyproterone acetate (CPA) plus Tamoxifen (TAM). Recently, we performed a multicenter double blind study on BPH patients treated with the association CPA plus Serenoa Repens. A statistically significant difference in prostate volume reduction between the groups treated with the combinations and those with the monotherapies was observed. The development of new compounds, such as 5 alpha reductase and aromatase inhibitors, consents to introduce a combination therapy with less side effects. A second pharmacological association may be obtained with drugs acting on the mechanical and others acting on the dynamic (alpha blockers) component of BPH. This combination may associate the early symptomatic effect of alpha blockers with the long term results of a 5 alpha reductase inhibitor, antiestrogen or aromatase inhibitor.

Bromocriptine↗
PubMed1993

Pathology of BPH.

Much research has been conducted to determine which tissue (epithelium or stroma) in the prostate gives rise to benign prostatic hyperplasia (BPH). Considering that BPH displays two structural compartments, stromal and epithelial and that the periurethral and transitional regions are particularly involved, the immunohistochemical and regional evaluation of steroid receptors concentration, 5 alpha reductase, DHT and estrogen activity, may show important data on the role of these factors in BPH development. We started a immunohistochemical study on the epidermal growth factor (EGF) concentrations in the periurethral, central and pericapsular zones of BPH samples, considering the stroma-epithelium ratio; investigations are performed on BPH patients submitted to transvesical prostatectomy. Considering that the periurethral zone is particularly involved in BPH, the presence of high concentration of growth factors in this region, may support the concept of their involvement in BPH.

Adult↗
PubMed1993

[Protection of the ischemic myocardium].

The Authors review several pharmacological interventions aimed at protecting the ischemic myocardium. Drugs which have been widely used in the treatment of ischemic heart diseases, such as beta-blockers, nitrates and calcium-antagonists, are able to delay the development of ischemic injury if administered before the beginning of ischemia, but their clinical effectiveness is limited. The new drugs which are presently investigated are designed to counteract the molecular mechanisms which mediate irreversible tissue injury, namely cytosolic calcium overload, cellular hyperosmolarity, and free radical production. In particular, interventions able to interfere with the release of calcium from its intracellular stores would be of major importance. In this regards, it is interesting to point out that derivatives of phenylalkylamine calcium-antagonists have been reported to modulate the opening probability of sarcoplasmic reticulum calcium channels.

Adenosine↗
PubMed1993

[Etiopathogenesis of dilated cardiomyopathies].

This study was carried out on 43 patients affected by dilated cardiomyopathy to investigate some of the etiopathological hypotheses on this illness. The Authors investigated: the persistence of virus genoma (coxsackie, HBV) on endomyocardial biopsies; the pattern of the II class major histocompatibility complex (MHC) were in the blood lymphocytes; the microvascular aspect of coronary circulation in the endomyocardial biopsies. Finally, in a separated group of 19 patients, the microvascular circulation was studied on skin biopsies and correlated with diabetic, valvular and normal subject. The results showed a 14% positivity for the presence of the virus genoma and a significant predominate of DR5 in the II class MHC of patients with a worse ventricular function. Capillary vessels of the coronary microcirculation were dilated in the 48% of the patients, especially in more compromised subjects. Viral myocarditis seem to play a role in the etiopathogenesis of dilated cardiomyopathies (DCM) and the pattern of MHC could influence the progression of the illness. The microcirculation is probably a pathophysiological aspect. No etiological hypothesis seems to predominate.

Adult↗
PubMed1993

Inhibition of lung and liver tumor colonies in mice pretreated with suramin.

The effect of suramin on B16F10 melanoma lung colonies and M5076 reticulosarcoma liver metastasis formation was evaluated in C57B1/6 female mice. Single i.v. doses of 200 mg/kg suramin given 48 and 24 h prior to tumor cell injection significantly inhibited metastasis formation in both models, whereas the same treatment administered 24 h after cell injection was ineffective. A dose-response experiment in the B16F10 melanoma model showed that inhibition of lung colony formation was still significant with 50 mg/kg pretreatment, whereas a borderline effect was observed at 10 mg/kg. At the effective doses, the plasma and organ concentrations of suramin were far below those needed to exert significant in vitro cytotoxic or cytostatic effects on B16F10 and M5076 cells. Thus, in addition to the antineoplastic effect of suramin our results indicate a potential antimetastatic role for this compound.

Animals↗
PubMed1993

Comparison of two different HPLC hydroxylapatite matrices for resolution of IgG idiotypes.

High-performance liquid chromatography hydroxylapatite (HPHT) is a well-known matrix utilized to separate macromolecules by differential surface binding to phosphate or calcium sites on the matrix. HPHT columns are commercially available packed with a crystalline structure formed of angular particles conferring a relatively poor elastic resistance to the matrix. In the present paper, we compare a conventional HPHT column to a new ceramic-type hydroxylapatite, which consists of globular particles providing a more mechanically stable matrix. The two hydroxylapatite matrices were compared in the purification of monoclonal antibodies produced by a hybridoma secreting three different types of antibodies. The two HPHT columns were able to separate the three antibodies molecules with equivalent peak resolution, and immunoreactivity analysis identified the active idiotype. HPLC columns packed with the ceramic hydroxylapatite resin exhibited a higher mechanical resistance than the crystalline material allowing significantly higher flow rates.

Animals↗