L'Azione Fisiologica del Nichel Sulle Piante di un Terreno Serpenitinoso

Abstract

The Author, on the basis of numerous results of pollen analysis on turfy-clayey deposits especially in Delta Padano, shows the gradual impoverishment, the main ancient species (Pinus haploxylon, Abies nordmanniana, Tsuga, Cedrus, Carya, Pterocarya, Zelkova, Castanea latifolia) suffered from during middle and upper Pleistocene.     

Pyridazinopsoralens of wide chemotherapeutic interest

The synthesis of new 6,10-dimethylpyridazino[4,5-h]psoralens, carrying no (4), one (5), or two (6–9) dialkylaminoalkylcarboxamide side chains on the pyridazine ring is reported. All compounds exert a significant photoantiproliferative activity. Moreover, the derivatives characterised by the protonable side chains show a notable cytotoxicity in the dark. The investigation on the mechanism of action demonstrated the capacity to intercalate into DNA base pairs and to inhibit the relaxation activity of topoisomerase II.     

Double anchorage to the membrane and intact inter-chain disulfide bond are required for the low pH induced entry of tetanus and botulinum neurotoxins into neurons

Tetanus and botulinum neurotoxins are di-chain proteins that cause paralysis by inhibiting neuroexocytosis. These neurotoxins enter into nerve terminals via endocytosis inside synaptic vesicles, whose acidic pH induces a structural change of the neurotoxin molecule that becomes capable of translocating its L chain into the cytosol, via a transmembrane protein-conducting channel made by the H chain. This is the least understood step of the intoxication process primarily because it takes place inside vesicles within the cytosol. In the present study, we describe how this passage was made accessible to investigation by making it to occur at the surface of neurons. The neurotoxin, bound to the plasma membrane in the cold, was exposed to a warm low pH extracellular medium and the entry of the L chain was monitored by measuring its specific metalloprotease activity with a ratiometric method. We found that the neurotoxin has to be bound to the membrane via at least two anchorage sites in order for a productive low-pH induced structural change to take place. In addition, this process can only occur if the single inter-chain disulfide bond is intact. The pH dependence of the conformational change of tetanus neurotoxin and botulinum neurotoxin B, C and D is similar and take places in the same slightly acidic range, which comprises that present inside synaptic vesicles. Based on these and previous findings, we propose a stepwise sequence of molecular events that lead from toxin binding to membrane insertion.     

Mass spectrometry-based identification of the tumor antigen UN1 as the transmembrane CD43 sialoglycoprotein

The UN1 monoclonal antibody recognized the UN1 antigen as a heavily sialylated and O-glycosylated protein with the apparent molecular weight of 100-120 kDa; this antigen was peculiarly expressed in fetal tissues and several cancer tissues, including leukemic T cells, breast, and colon carcinomas. However, the lack of primary structure information has limited further investigation on the role of the UN1 antigen in neoplastic transformation. In this study, we have identified the UN1 antigen as CD43, a transmembrane sialoglycoprotein involved in cell adhesion, differentiation, and apoptosis. Indeed, mass spectrometry detected two tryptic peptides of the membrane-purified UN1 antigen that matched the amino acidic sequence of the CD43 intracellular domain. Immunological cross-reactivity, migration pattern in mono- and bi-dimensional electrophoresis, and CD43 gene-dependent expression proved the CD43 identity of the UN1 antigen. Moreover, the monosaccharide GalNAc-O-linked to the CD43 peptide core was identified as an essential component of the UN1 epitope by glycosidase digestion of specific glycan branches. UN1-type CD43 glycoforms were detected in colon, sigmoid colon, and breast carcinomas, whereas undetected in normal tissues from the same patients, confirming the cancer-association of the UN1 epitope. Our results highlight UN1 monoclonal antibody as a suitable tool for cancer immunophenotyping and analysis of CD43 glycosylation in tumorigenesis.     

Molecular mechanisms generating and stabilizing terminal 22q13 deletions in 44 subjects with Phelan/McDermid syndrome

In this study, we used deletions at 22q13, which represent a substantial source of human pathology (Phelan/McDermid syndrome), as a model for investigating the molecular mechanisms of terminal deletions that are currently poorly understood. We characterized at the molecular level the genomic rearrangement in 44 unrelated patients with 22q13 monosomy resulting from simple terminal deletions (72%), ring chromosomes (14%), and unbalanced translocations (7%). We also discovered interstitial deletions between 17-74 kb in 9% of the patients. Haploinsufficiency of the SHANK3 gene, confirmed in all rearrangements, is very likely the cause of the major neurological features associated with PMS. SHANK3 mutations can also result in language and/or social interaction disabilities. We determined the breakpoint junctions in 29 cases, providing a realistic snapshot of the variety of mechanisms driving non-recurrent deletion and repair at chromosome ends. De novo telomere synthesis and telomere capture are used to repair terminal deletions; non-homologous end-joining or microhomology-mediated break-induced replication is probably involved in ring 22 formation and translocations; non-homologous end-joining and fork stalling and template switching prevail in cases with interstitial 22q13.3. For the first time, we also demonstrated that distinct stabilizing events of the same terminal deletion can occur in different early embryonic cells, proving that terminal deletions can be repaired by multistep healing events and supporting the recent hypothesis that rare pathogenic germline rearrangements may have mitotic origin. Finally, the progressive clinical deterioration observed throughout the longitudinal medical history of three subjects over forty years supports the hypothesis of a role for SHANK3 haploinsufficiency in neurological deterioration, in addition to its involvement in the neurobehavioral phenotype of PMS.     

A novel tetrahydrobenzoangelicin with dark and photo biological activity

The synthesis of 8,9,10,11-tetrahydro-5-(3-dimethylaminopropoxy)-4-methylbenzofuro[2,3-h]coumarin (5) is described. The new compound showed the ability to inhibit cell growth both upon UVA irradiation and in the dark. The investigation on the mechanism of action highlighted the capacity of 5 to covalently photoadd to thymine, as demonstrated by the isolation and characterization of the 4',5'-monoadduct. Furthermore, in the ground state 5 interferes with the topoisomerase II relaxation activity, suggesting that this enzyme could constitute a molecular target responsible for the dark antiproliferative effect.     

Cholesterol-based nucleolipid-ruthenium complex stabilized by lipid aggregates for antineoplastic therapy

A novel ruthenium complex, linked to a cholesterol-containing nucleolipid (named ToThyCholRu), stabilized by lipid aggregates for antineoplastic therapy is presented. In order to retard the degradation kinetics typically observed for several ruthenium-based antineoplastic agents, ToThyCholRu is incorporated into a liposome bilayer formed by POPC. The resulting nanoaggregates contain up to 15% in moles of the ruthenium complex, and are shown to be stable for several weeks. The liposomes host the ruthenium-nucleolipid complex with the metal ion surrounded by POPC lipid headgroups and the steroid moiety inserted in the more external acyl chain region. These ruthenium-containing liposomes are more effective in inhibiting the growth of cancer cells than a model NAMI-A-like ruthenium complex, prepared for a direct evaluation of their anti-proliferative activity. These results introduce new perspectives in the design of innovative transition-metal-based supramolecular systems for anticancer drug vectorization.     

p300/CBP acetyl transferases interact with and acetylate the nucleotide excision repair factor XPG

Nucleotide excision repair (NER) is an important DNA repair mechanism through which cells remove bulky DNA lesions. Following DNA damage, the histone acetyltransferase (HAT) p300 (also referred to as lysine acetyltransferase or KAT) is known to associate with proliferating cell nuclear antigen (PCNA), a master regulator of DNA replication and repair processes. This interaction, which results in HAT inhibition, may be dissociated by the cell cycle inhibitor p21^CDKN1A, thereby restoring p300 activity; however, the role of this protein interplay is still unclear. Here, we report that silencing p300 or its homolog CREB-binding protein (CBP) by RNA interference (RNAi) significantly reduces DNA repair synthesis in human fibroblasts. In addition, we determined whether p300 and CBP may associate with and acetylate specific NER factors such as XPG, the 3′-endonuclease that is involved in the incision/excision step and is known to interact with PCNA. Our results show that p300 and CBP interact with XPG, which has been found to be acetylated in vivo. XPG is acetylated by p300 in vitro, and this reaction is inhibited by PCNA. Knocking down both p300/CBP by RNAi or by chemical inhibition with curcumin greatly reduced XPG acetylation, and a concomitant accumulation of the protein at DNA damage sites was observed. The ability of p21 to bind PCNA was found to regulate the interaction between p300 and XPG, and an abnormal accumulation of XPG at DNA damage sites was also found in p21^−/− fibroblasts. These results indicate an additional function of p300/CBP in NER through the acetylation of XPG protein in a PCNA–p21 dependent manner.     

Persistence of carbapenem-resistant Acinetobacter baumannii strains in an Italian intensive care unit during a forty-six month study period

The aims of this study were to analyze carbapenem-resistance Acinetobacter baumannii isolates (CRAB) and their molecular epidemiology in an ICU of Southern Italy. Clinical outcomes and therapeutic management of patients are also described. The study was performed from January 2007 to October 2010. The presence of carbapenemases was determined by PCR. Strains were typed by PFGE. All A. baumannii isolates were carbapenem-resistant with imipenem MIC≥16 μg/mL. Molecular characterization showed the occurrence of a predominant clone. The most frequent infection by CRAB was ventilator-associated pneumonia; colistin was the drug of choice for this infection. The therapy was safe in all cases except in one where therapy was suspended due to the onset of acute renal failure. We documented the presence of CRAB in this ICU, besides the occurrence of a predominant clone, over all the study period. Despite the infection control procedures used, intra-facility A. baumannii transmission is evident as well as the significant capacity for long-term survival in the hospital environment.