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Biomedical subjects

M Mariani

Publications and source records attributed to M Mariani.

At least 127 records · Page 7Linked to original sources
PubMed1995

Recombinant proteins L and LG: efficient tools for purification of murine immunoglobulin G fragments.

In order to improve antibody purification methods, recombinant proteins L and LG were tested in the purification of murine monoclonal immunoglobulin G (IgG) and its fragments. After affinity constant evaluation in different buffer systems, high-performance affinity chromatographic columns were prepared by coupling the proteins to Affi-prep 10 resin and tested with eight different murine monoclonal antibodies and their fragments of different isotypes. Affinity chromatographic experiments confirmed radioimmunoassay results showing that protein L bound 75% of the tested antibody fragments whereas protein LG had affinity for all the tested fragments. These results demonstrate that protein LG is the most powerful Ig-binding tool so far described.

Animals↗
PubMed1995

Bispecific monoclonal antibody anti-CD3 x anti-tenascin: an immunotherapeutic agent for human glioma.

Besides surgery, the therapeutic possibilities for the treatment of human gliomas include adoptive cellular immunotherapy, radioimmunotherapy, immunotherapy mediated by chemoimmunoconjugates and, more recently, bispecific monoclonal antibodies (biMAbs). Anti-CD3 x anti-tenascin (TN) is the first reagent of a number of biMAbs under investigation for prospective use in vivo to maximize the cell-mediated cytolytic potential of glioma patients. This biMAb originated from the fusion of 2 parental hybridomas, made resistant by retrovirus-mediated infection to the different metabolic drugs, geneticin and methotrexate, respectively. The resulting hybrid hybridomas were selected on the basis of the double specificity for CD3 and TN, cloned several times and grown under continuous metabolic pressure. The different families of recombinant antibodies were then purified by high-pressure liquid chromatography on hydroxylapatite columns. Immunohistochemical studies on tumor specimens of different origin and histotype have shown that the selected biMAb presented a distribution pattern similar to that of the parental anti-TN MAb, maintaining the same staining homogeneity and intensity. Moreover, the mitogenic activity of anti-CD3 x anti-TN biMAb on peripheral blood mononuclear cells was similar to that featured by the parental anti-CD3 MAb. Furthermore, the hybrid molecule induced TNF-alpha gene expression in activated PBMC. Finally, the anti-CD3 x anti-TN featured the desired killer targeting ability, being able to induce a significantly increased cytotoxic activity against TN+ tumor cells.

Antibodies, Bispecific↗
PubMed1995

Relation between dobutamine trans-thoracic echocardiography, 99Tcm-MIBI and 18FDG uptake in chronic coronary artery disease.

The relationships between rest conditions of myocardial asynergy, response to dobutamine administration, perfusion and glucose metabolism were examined in 12 patients with chronic coronary artery disease and left ventricular dysfunction. We evaluated (1) rest and stress myocardial perfusion by 99Tcm-methoxyisobutylisonitrile (MIBI) and single photon emission tomography (SPET), (2) rest myocardial segmental wall motion by trans-thoracic echocardiography and low-dose dobutamine, and (3) myocardial metabolism by [18F]-2-fluoro-2-deoxy-D-glucose (18-FDG) and positron emission tomography (PET), in the fasting state. The analysis was carried out on 16 left ventricular myocardial segments. The SPET studies were analysed semi-quantitatively by normalization to the peak activity. Wall motion was assessed by a visual score. An 18FDG index was determined as the tissue/blood pool radioactivity ratio in each segment. The results showed: (1) remarkably good agreement between the number of dobutamine responsive segments and 18FDG positive segments among those that were only moderately hypoperfused and hypokinetic; (2) a smaller number of dobutamine responsive segments than 18FDG positive segments among those that were hypoperfused and akinetic; and (3) the presence of 18FDG in 50% of the segments that were severely hypoperfused and akinetic or dyskinetic and without improvement with dobutamine. These results indicate that in severely hypoperfused and akinetic or dyskinetic segments, trans-thoracic echocardiography under inotropic stimulation provides little additional information compared with that obtained with rest echocardiography and perfusion studies; the assessment of 18FDG uptake provides information that is complementary to that obtained by perfusion assessment, rest and dobutamine trans-thoracic echocardiography.

Adult↗
PubMed1995

Interaction between gallopamil and cardiac ryanodine receptors.

1. In a sarcoplasmic reticulum fraction obtained from rat hearts, the analysis of equilibrium [3H]-ryanodine binding showed high and low affinity sites (KD = 1.3 nM and 2.8 microM, Bmax = 2.2 pmol mg-1 and 27.8 pmol mg-1). The dissociation rate constant increased at 1 microM vs 4 nM [3H]-ryanodine concentration, and micromolar ryanodine slowed the dissociation of nanomolar ryanodine. 2. The binding of 4 nM [3H]-ryanodine was not affected by gallopamil, while the binding of 100 nM to 18 microM [3H]-ryanodine was partly displaced. Data analysis suggested that gallopamil inhibited low affinity [3H]-ryanodine binding, with IC50 in the micromolar range. 3. Gallopamil decreased the dissociation rate constant of 1 microM [3H]-ryanodine. While gallopamil alone did not affect the dissociation of 4 nM [3H]-ryanodine, gallopamil and micromolar ryanodine slowed it to a greater extent than micromolar ryanodine alone. 4. Our results are consistent with the hypothesis that the ryanodine receptor is a negatively cooperative oligomer, which undergoes a sequential alteration after ryanodine binding. Gallopamil has complex actions: it inhibits ryanodine binding to its low affinity site(s), and probably modulates the cooperativity of ryanodine binding and/or the transition to a receptor state characterized by slow ryanodine dissociation. These molecular actions could account for the previously reported effect of gallopamil on the sarcoplasmic reticulum calcium release channel.

Animals↗
PubMed1995

Postischemic changes in cardiac sarcoplasmic reticulum Ca2+ channels. A possible mechanism of ischemic preconditioning.

We investigated the modifications of cardiac ryanodine receptors/sarcoplasmic reticulum Ca2+ release channels occurring in ischemic preconditioning. In an isolated rat heart model, the injury produced by 30 minutes of global ischemia was reduced by preexposure to three 3-minute periods of global ischemia (preconditioning ischemia). The protection was still present 120 minutes after preconditioning ischemia but disappeared after 240 minutes. Three 1-minute periods of global ischemia did not provide any protection. In the crude homogenate obtained from ventricular myocardium, the density of [3H]ryanodine binding sites averaged 372 +/- 18 fmol/mg of protein in the control condition, decreased 5 minutes after preconditioning ischemia (290 +/- 15 fmol/mg, P < .01), was still significantly reduced after 120 minutes (298 +/- 17 fmol/mg, P < .05), and recovered after 240 minutes (341 +/- 21 fmol/mg). Three 1-minute periods of ischemia did not produce any change in ryanodine binding. The Kd for ryanodine (1.5 +/- 0.3 nmol/L) was unchanged in all cases. In parallel experiments, the crude homogenate or a microsomal fraction was passively loaded with 45Ca, and Ca(2+)-induced Ca2+ release was studied by the quick filtration technique. In both preparations, the rate constant of Ca(2+)-induced Ca2+ release decreased 5 and 120 minutes after preconditioning ischemia (homogenate values: 19.7 +/- 1.4 and 18.9 +/- 0.9 s-1 vs a control value of 25.4 +/- 1.7 s-1, P < .05 in both cases) and recovered after 240 minutes (23.0 +/- 1.9 s-1). The Ca2+ dependence of Ca(2+)-induced Ca2+ release was not affected by preconditioning ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

The use of ACTH and beta-endorphin levels to measure the stress impact and safety of extracorporeal lithotripsy.

The authors measured the plasma levels of beta-endorphin and adrenocorticotropic hormone (ACTH) related to pain in 11 urologic patients who underwent extracorporeal lithotripsy. The study included eight male and three female patients (aged 24 to 65 years) with single kidney stones of less than 20 mm who were treated with the Lithoring Multi-One device. The device delivered 2,000 shock waves from 18 kV to 25 kV, increasing by 1 kV every 250 shock waves. Three patients experienced pain, but only one required intravenous analgesia. The assay of plasmatic ACTH and beta-endorphin is proposed to control the safety and the stress impact of new devices and techniques. In addition, the study demonstrates the medicolegal relevance of such an assay in the evaluation of pain.

Adrenocorticotropic Hormone↗
PubMed1995

["Canadian" hernioplasty with embrication. Anatomy, surgical technic, and personal experience].

Among the numerous operations proposed for the treatment of inguinal hernia, the authors utilised Shouldice's method of hernioplasty in over 400 cases of non-recurrent hernia. After drawing attention to a few anatomical type specifications regarding the inguinal canal structures, the "Canadian" surgical technique is described in detail. The authors analyse the various methods of hernioplasty now used and conclude that Shouldice's method should be considered elective in the treatment of primary direct inguinal hernias and voluminous indirect hernias in adults.

Adult↗
PubMed1995

Are dihydropyridine receptors downregulated in the ischemic myocardium?

OBJECTIVE: We investigated the effect of ischemia on cardiac dihydropyridine receptors, which correspond to L-type sarcolemmal calcium channels. METHODS: Isolated working rat hearts were perfused aerobically for 10 min, and then subjected to 10-60 min of global ischemia. Control hearts were perfused aerobically for 30 min. [3H]PN 200-110 binding was measured in the unfractionated homogenate, in a crude membrane preparation and in a microsomal fraction. RESULTS: In the homogenate obtained from control hearts, the Kd and Bmax averaged 0.23 +/- 0.05 nM and 84 +/- 4 fmol/mg protein, respectively, and ischemia did not produce any significant change in these variables. Similar results were obtained in the crude membrane preparation (Kd = 0.29 +/- 0.08 nM, Bmax = 113 +/- 7 fmol/mg, yield of binding sites = 98 +/- 6%, no significant change in these variables during ischemia). On the contrary, in the microsomal fraction, the Bmax for [3H]PN 200-110 decreased after ischemia (115 +/- 15 fmol/mg after 20 min of ischemia vs. 190 +/- 34 fmol/mg in the control condition, P < 0.05), without any change in the Kd. In this fraction, the yield for PN 200-110 binding sites was 4.7 +/- 0.6% in the control condition and 2.8 +/- 0.5% after ischemia (P < 0.05). The yield of other sarcolemmal markers such as [3H]quinuclidinyl benzylate and [3H]ouabain binding sites was not reduced in the microsomal fraction obtained ischemic hearts. CONCLUSIONS: The total number of cardiac dihydropyridine binding sites was not downregulated during ischemia, although their distribution after tissue fractionation was slightly modified, possibly reflecting receptor redistribution between different subcellular pools.

Animals↗
PubMed1994

1H, 13C, and 15N resonance assignments and secondary structure analysis of the HU protein from Bacillus stearothermophilus using two- and three-dimensional double- and triple-resonance heteronuclear magnetic resonance spectroscopy.

Nearly complete 1H, 13C, and 15N resonance assignments have been obtained for the protein HU from Bacillus stearothermophilus (dimer, 19.5 kDa) using double- and triple-resonance 2D and 3D NMR experiments. This has resulted in assignments of 91% of the observable protons, 98% of all 13C, and 92% of all 15N nuclei. NOEs obtained from a 3D time-shared NOESY-(13C,15N)-HSQC spectrum, exchange data of amide protons, and chemical shifts of the 1H alpha, 1HN, 13C beta, 13C alpha, 13CO, and 15N nuclei have been used to identify the secondary structure elements. Three alpha-helices (residues 3-13, 18-37, and 83-90) and three extended strands (residues 40-45, 48-62, and 67-82) have been found in HU. The arrangement of these elements of secondary structure is very similar to the X-ray structure [Tanaka et al. (1984) Nature 310, 376-381; White et al. (1989) Proteins 5, 281-288]. The conformation of the proposed DNA-binding region of HU, i.e., an antiparallel beta-hairpin, was not observed previously in the X-ray structure. In the NMR structure long range NOEs in the beta-arm region (residues 53-76) suggest a distortion between residue Pro-72 and Ala-73 and between Pro-63 and Gln-64 with concomitant distortions in the opposite strand. The NOE data indicate further that the loop region in the DNA-binding arms of HU is arranged as a type I beta-turn from Pro-63 to Gly-66.

Amino Acid Sequence↗
PubMed1994

New sulfonated distamycin A derivatives with bFGF complexing activity.

Tumor-induced neoangiogenesis is an essential event for solid tumor growth. Therefore, a compound able to block angiogenesis-promoting factors could have antitumor activity. The polysulfonated naphthylurea suramin is hypothesized to have this mode of action. A series of sulfonated distamycin A derivatives have been synthesized with the objective of identifying novel compounds able to complex basic fibroblastic growth factor (bFGF) and other factors involved in tumour angiogenesis, and consequently to block the angiogenic process. These new compounds have been characterized for their ability to inhibit bFGF binding, in vivo bFGF-induced angiogenesis and neovascularization of the chorioallantoic membrane, in comparison with suramin. The two most active compounds, FCE 26644 [7,7'-(carbonyl-bis(imino-N-methyl-4,2-pyrrolecarbonyl-imino(N-met hyl-4,2- pyrrole)carbonylimino))-bis(1,3-naphthalenedisulfonic acid)] and FCE 27164 [7,7'-(carbonyl-bis(imino-N-methyl-4,2-pyrrolecarbonyl-imino(N-met hyl-4,2- pyrrole) carbonylimino)-bis (1,3,5-naphthalenetrisulfonic acid)] have been selected for extended evaluation. Both compounds are active in inhibiting platelet-derived growth factor beta (PDGF beta) and interleukin-1 beta binding. Two different assays have been performed to study their mode of action: the sequential binding assay on bFGF and PDGF receptors and the bFGF-induced tyrosine phosphorylation assay. The results of the two assays are in agreement and indicate that no activity is observed if FCE 26644, FCE 27164 and suramin are administered as pretreatment, when a direct interaction of the compounds with bFGF and PDGF receptors is required. Conversely, inhibitory activity is observed when the compounds are allowed to form complexes with the growth factors themselves.

3T3 Cells↗