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Biomedical subjects

A Mattioli

Publications and source records attributed to A Mattioli.

At least 73 records · Page 4Linked to original sources
PubMed1979

[Selective arterial perfusion with antienzymes in experimental acute pancreatitis. Preliminary experience].

Authors analyze some results obtained treating, with selective arterial perfusion (using antienzymes), experimental acute pancreatitis in dogs (fifteen). The first dogs' group was used to perform several experimental acute pancreatitis; the second group was treated by selective arterial perfusion and was related to group of dogs treated by i.v. antienzymes drugs. Histological and biochemical data are discussed. The results obtained with arterial perfusion are preliminary referred as better than classic i.v. antienzymes drugs therapy.

Acute Disease↗
PubMed1977

[Behavior of the local lymphatic system after aorta-iliaco-femoro-popliteal reconstruction].

As a result of the observation of oedemas of the lower extremities and lymphorrhoea in the immediate postoperative course of surgical reconstruction of the aorto-iliaco-femoro-popliteal arterial axis (and on the basis of similar cases in the literature), the participation of the lower extremity return circulation in this facet of vascular surgery has been documented. The venous system was never impaired whereas the local lymphatic system was always damaged by surgical aggression on the arterial vessels. However, the extensive anatomical lesions shown up by lymphography are not reflected in evident clinical signs; whenever oedema or lymphorrhoea of the surgical wounds are observed, these symptoms are always of slight importance and easily and quickly resolved. At long-term follow-up, no clinical evidence of impairment ot the venous and lymphatic venous return circulation was ever encountered. For prophylactic purposes the lymphatic structure encountered during the operation should be carefully ligated to counteract another dangerous complication: infection.

Aorta↗
PubMed1976

Inhibition of protein synthesis in vitro by crotins and ricin. Effect on the steps of peptide chain elongation.

The effects of crotin I and crotin II on the partial reactions of polypeptide chain elongation were investigated and compared with the known effects of ricin. Crotin II was a more powerful inhibitor than crotin I, but no qualitative differences between the two crotins were found. Rat liver ribosomes, preincubated with crotins and washed through sucrose gradients, remained inactive in protein synthesis. Among the individual steps of elongation, the peptidyltransferase reaction was unaffected by crotins, but some of the reactions that involve the interaction of elongation factors 1 and 2 with ribosomes were modified. A strong inhibition of the binding of elongation factor 2 to ribosomes and a stimulation of the elongation factor2-dependent GTP hydrolysis were observed; this indicates the formation of a very unstable elongation factor 2--GDP--ribosome complex, which, however, allows a single round of translocation to take place in the presence ofelongation factor 2 and added GTP. The elongation factor 1-dependent GTP hydrolysis was inhibited by crotins, whereas the enzymic binding of aminoacyl-tRNA, to both rat liver and Artemia salina ribosomes, was scarcely affected. In a protein-synthesizing system the inhibition by crotins and by ricin leads to a block of the nascent peptides on the ribosomal aminoacyl-tRNA site, an effect consistent with inhibition at the level of translocation. The mechanism of action of crotins appears to be very similar to that of ricin.

Animals↗
PubMed1976

Effect of elongation factor 2 and of adenosine diphosphate-ribosylated elongation factor 2 on translocation.

1. The effect of elongation factor 2 (EF 2) and of adenosine diphosphate-ribosylated elongation factor 2 (ADP-ribosyl-EF 2) on the shift of endogenous peptidyl-tRNA from the A to the P site of rat liver ribosomes (measured by the peptidyl-puromycin reaction) and on the release of deacylated tRNA (measured by aminoacylation) was investigated. 2. Limiting amounts of EF2, pre-bound or added to ribosomes, catalyse the shift of peptidyl-tRNA in the presence of GPT; when the enzyme is added in substrate amounts GMP-P(CH2)P [guanosine (beta, gamma-methylene)triphosphate] can partially replace GTP. ADP-ribosyl-EF 2 has no effect on the shift of peptidyl-tRNA when present in catalytic amounts, but becomes almost as effective as EF 2 when added in substrate amounts together with GTP; GMP-P(CH2)P cannot replace GTP. 3. The release of deacylated tRNA is induced only by substrate amounts of added EF 2 and also occurs in the absence of guanine nucleotides. In this reaction ADP-ribosyl-EF 2 is only 25% as effective as EF 2 in the absence of added nucleotide, but becomes 60-80% as effective in the presence of GTP or GMP-P(CH2)P. 4. The results obtained on protein-synthesizing systems are consistent with the hypothesis that ADP-ribosyl-EF 2 can operate a single round of translocation followed by binding of aminoacyl-tRNA and peptide-bond formation. 5. From the data obtained with the native enzyme it is concluded that the two moments of translocation require different conditions of interaction of EF 2 with ribosomes; it is suggested that the shift of peptidyl-tRNA is catalysed by EF 2 pre-bound to ribosomes, and that the release of tRNA is induced by a second molecule of interacting EF 2. The hydrolysis of GTP would be required for the release of pre-bound EF 2 from ribosomes. 5. The inhibition of the utilization of limiting amounts of EF 2 on ADP-ribosylation is very likely the consequence of a concomitant decrease in the rate of association and dissociation of the enzyme from ribosomes.

Adenosine Diphosphate Sugars↗
PubMed1975

Inhibition by ricin of protein synthesis in vitro. Inhibition of the binding of elongation factor 2 and of adenosine diphosphate-ribosylated elongation factor 2 to ribosomes.

The binding of EF2 (elongation factor 2) and of ADP-ribosyl-EF 2 to rat liver ribosomes is inhibited by ricin. This result suggests that the native enzyme and its ADP-ribose derivative have the same or closely related binding sites on the ribosome. The inhibition by ricin of the binding of EF 2 to ribosomes is consistent with the previous observation that ricin affects EF 2-catalysed translocation during polypeptide chain elongation.

Adenosine Diphosphate↗
PubMed1975

Relationship between elongation factor I- and elongation factor II- dependent guanosine triphosphatase activities of ribosomes. Inhibition of both activities by ricin.

The elongation factor 1- and elongation factor 2-dependent GTPase (guanosine triphosphatase) activities of ribosomes are inhibited by ricin, a toxic protein known to inactivate the 60S ribosomal subunit. It is suggested that also in eukaryotic ribosomes a "GTPase site', located on the larger subunit, is common to the two elongation factors.

Animals↗