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E Rizzi

Publications and source records attributed to E Rizzi.

25 records · Page 2Linked to original sources
PubMedDate not supplied

The use of crown ethers in peptide chemistry-V. Solid-phase synthesis of peptides by the fragment condensation approach using crown ethers as non-covalent protecting groups.

We have previously described the conditions by which peptide synthesis by the solid-phase fragment condensation approach can be carried out using crown ethers as non-covalent protection for the N alpha-amino group. Here we demonstrate that the procedure can be extended to large, partially protected peptide fragments possessing free Lys and/or Arg residues. The first step was to ensure that complex formation on the side chain of amino acids was not detrimental to the methodology and exhibited the same solubility and coupling properties as N alpha-complexed peptides. Thus, a model hexapeptide was synthesized using Fmoc chemistry containing Lys and Arg residues, which, when complexed with 18-Crown-6, was readily soluble in DCM and coupled quantitatively to a resin-bound tetrapeptide. Two tripeptides were then prepared, one containing a free Ser residue, the other free Tyr, to examine the possible occurrence of side reactions. After coupling using standard conditions only the former tripeptide exhibited the formation of the O-acylation by-product (5%). Another model hexapeptide containing Lys, Tyr, Ser and Asp protected with a TFA-stable adamantyl group was complexed with 18-Crown-6 and coupled to the resin-bound tetrapeptide with near quantitative yield. Extending the length of the peptide to 21 and 40 residues, which represent sequences Gly52 to Leu72 (21-mer) and Pro33 to Leu72 (40-mer) from Rattus norvegicus chaperonin 10 protein, respectively, resulted in partially protected fragments that were readily soluble in water, thus enabling purification by RP-HPLC. Complexation with 18-Crown-6 gave two highly soluble products that coupled to resin-board tetramer with 68% and 50% coupling efficiencies for the 21-mer and 40-mer, respectively. Treatment with 1% DIEA solutions followed by acidolytic cleavage and purification of the major product confirmed that the correct product has been formed, when analysed by amino acid analysis and ESI-MS. These results served to extend the methodology of non-covalent protection of large partially protected peptide fragments for the stepwise fragment condensation of polypeptides.

Amino Acids↗
PubMedDate not supplied

Programmed cell death in colorectal carcinogenesis.

The most studied mechanism of malignant transformation has been cell proliferation. The relationship between programmed cell death (apoptosis), cell proliferation, and apoptosis regulatory genes (p53 and bcl-2), was studied in normal colonic epithelium, 26 sporadic adenomas both early and late, 25 FAP adenomas, and 34 carcinomas. We showed a decrease in programmed cell death and an increase in cell proliferation during the transition from adenoma to carcinoma. The increase of expression of p53 from early (10%) to late adenomas (87%) contrasted with the decrease of bcl-2 staining. Sixty-two per cent and 23% of carcinomas were reactive for p53 and bcl-2 respectively. Abnormal early activation of the bcl-2 gene, rather than late p53 gene mutation appears to be responsible for inhibition of apoptosis in colorectal carcinogenesis. bcl-2 was higher in FAP adenomas than in sporadic cases, and in carcinomas favouring the accumulation of long-living cells, which are more subject to mutation and thus cancerization.

Apoptosis↗
PubMedDate not supplied

[Evaluation of central venous catheters by endocavitary ECG].

Jugular vein catheterization (JVC) is adopted for blood access in patients with acute renal failure, chronic renal failure and when patients demonstrate traditional vascular access (VA) failure. We believe that the best technique, first described by Serafini et al, to establish the position of a central venous catheter (CVC) is endocavitary electrocardiography (EC-ECG) and its use is recommended in all uremic patients requiring hemodialysis (HD). This technique uses the tip of the CVC as a reference point in standard electrocardiography. From 2001 to March 2004, we successfully applied this CVC technique in 33 patients requiring HD. The EC-ECG technique is a method that complies with the Food and Drug Administration guidelines regarding catheter tip location in uremic patients.

Catheterization, Central Venous↗
PubMedDate not supplied

Clinical, laboratory and immunogenetic aspects of post-traumatic psoriatic arthritis: a study of 25 patients.

OBJECTIVE: In a previous study we demonstrated that the prevalence of trauma preceding arthritis was higher in patients with psoriatic arthritis (PsA) than in patients with rheumatoid arthritis (RA) or ankylosing spondylitis (AS); of 300 consecutive patients with PsA, 25 (8%) had a history of trauma before (< 3 months) the onset of the disease. The present study was carried out to characterize the clinical, laboratory and immunogenetic profiles of post-traumatic (PT)-PsA. PATIENTS AND METHODS: The clinical and laboratory features of 25 patients with PT-PsA were studied at onset (first 6 months) and after a follow-up period of 1-7 years, and were compared with those of 275 PsA patients without any history of trauma (nonPT-PsA). HLA typing was performed in PT-PsA patients, and synovial fluid (SF) analysis, including interleukin (IL)-1 and IL-6 determinations, was carried out in 12 subjects with PT-PsA and in 32 with nonPT-PsA. RESULTS: No differences were observed between PT-PsA and nonPT-PsA patients with regard to their clinical evolution. ESR (p < 0.0001) and CRP (p = 0.005) were higher in PT-PsA than in nonPT-PsA patients at disease onset but not after follow-up. No differences were found in the other blood indices. SF analysis revealed higher IL-6 levels in PT-PsA than in nonPT-PsA patients (p < 0.0005). CONCLUSION: Our study demonstrates that the prevalence of trauma preceding arthritis is higher in PsA than in RA or AS. Clinical and laboratory findings in patients with PT-PsA differed from those with nonPT-PsA only at disease onset (first six months), however, showing an abrupt clinical presentation and a more acute phase response. This pattern may be related to the higher levels of IL-6 found in the SF of PT-PsA than in nonPT-PsA patients. However, during the follow-up period the two groups became indistinguishable, and no difference was observed between PT-PsA and nonPT-PsA regarding the evolution of the disease.

Accidental Falls↗
PubMedDate not supplied

Clinical pathological and ploidic patterns of juvenile colon cancers.

Details of 197 colorectal carcinomas from 180 patients were retrieved from our files, with the aim of analyzing the clinical histories and pathological parameters of all patients up to 40 years, and to support these data with the results of the DNA content analysis of tumoral cells by static cytometry. The incidence of juvenile carcinomas in our series was 7%, with a high percentage (38%) of cases associated with preneoplastic conditions. Our findings show a higher frequency of mucinous (21.5%), poorly differentiated (55%) and diploid (29%) neoplasias with a higher incidence of carcinomas localized in the right colon (50%) in young patients than found in elderly one. However, juvenile carcinomas did not differ significantly from neoplasias in the elderly population, because some pathological parameters considered as unfavourable prognostic factors in the formers (e.g. increased incidence of mucinous and poorly differentiated carcinomas) are "balanced" by features suggesting a good outcome (e.g. higher frequency of diploid neoplasias).

Adenocarcinoma↗
PubMedDate not supplied

Gastric Malt lymphoma: a clinicopathological study.

The detection of HP infection by means of non invasive methods such as breath test and urease test, which are adopted alternatively to histological examination, can delay the diagnosis of early lymphomas. On the other hand the proved regression of gastric low grade Malt lymphomas after a successful HP eradication strongly suggests the need for early diagnosis. The aim of this study was to report the results of our experience with regard to clinical, endoscopic, histopathologic, and immunohistochemical features of gastric MALT lymphomas. We studied twenty-seven consecutive cases of gastric Malt lymphoma. HP presence in gastric mucosa was detected in all cases but endoscopy only in 40.7% of cases giving a diagnosis of suspected malignancy. In conclusion, it is very important to sample gastric mucosa in HP positive patients because the histological examination represents the most effective tool to detect lesions at the earliest and curable stage.

Adult↗