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Biomedical subjects

F Mazza

Publications and source records attributed to F Mazza.

At least 55 records · Page 3Linked to original sources
PubMed1988

Potential energy calculations on phenylalanine rotamers in different boat forms of proline-containing cyclic dipeptides.

Previous potential energy calculations have always indicated that the folded conformation is the most stable one for cyclic dipeptides containing benzylic side chains. We have carried out intramolecular van der Waals potential energy calculations on cyclo-(D-Phe-L-Pro), N-(N-phenylacetyl-L-alanyl)-cyclo-(L-Phe-D-Pro) and N-(pyruvoyl)-cyclo-(L-Phe-D-Pro) adopting the geometries found in their crystal structures. The calculations made on these compounds, having the peptide skeleton made of the same aminoacid residues but differing in the degree of buckling of the boat, show that there is a dependence between diketopiperazine ring and phenylalanine side-chain conformations. The folded conformer is preferred as long as it is allowed by the degree of buckling of the boat. When the boat becomes highly buckled, as in the case of the pyruvoyl derivative, the folded rotamer is no longer favoured. This is the first energy calculation to demonstrate that the folded rotamer is not always the most stable one.

Dipeptides↗
PubMed1988

Cisplatin and etoposide as second-line chemotherapy in patients with small cell lung cancer.

Twenty-seven evaluable patients with small cell lung cancer (SCLC) resistant to, or relapsed after induction combination chemotherapy (CT) were treated with etoposide (VP16) plus cisplatin (DDP). Previous treatment was: alternating CT with cyclophosphamide (C), adriamycin (A), methotrexate (M), procarbazine (P) (CAMP)/VP16, BCNU (B), hexamethylmelamine (H) (VP16 BH) in 16 patients; C, A, vincristine (CAV) in 6 patients; C, A, and VP16 (CAVP16) in 5 patients. We observed 2 (7%) complete responses (CR) and 9 (33%) partial responses (PR). Duration of CRs was 8 and 14 weeks, respectively. PRs lasted a median of 22 weeks (range 16-44). Seven of 21 (33%) patients previously treated with VP16 responded to DDP plus VP16 (D-V). These results confirm D-V regimen as active in SCLC patients even when heavily pretreated. Our 33% response in patients who had VP16 in their induction treatment regimen provides further evidence of an important potentiating effect of DDP, as reported in animal system.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

Non-invasive electrophysiological evaluation of calcium antagonist long-term therapy.

The evaluated effects of oral administration of verapamil, diltiazem, and nifedipine in patients with first degree A-V block by using a new noninvasive technique: signal averaged ECG. The study group consists of 5 females and 3 males ranging from 52 to 70 years old. All patients showed a first degree A-V block at surface ECG and an abnormal A-V time (suprahisian lengthening) during signal averaged ECG (SAECG). Verapamil 240 mg/daily, diltiazem 180 mg/day and nifedipine 30 mg/day were given separately for a week followed by a wash out period of 5 days before giving next drugs. An ECG and SAECG were performed before and after every administration. PR, A-H and H-V interval were evaluated in every recording. Verapamil and diltiazem induced a significant lengthening of A-V conduction (PR increase was 15.4% and 15.1%, respectively). No significant modification appeared after nifedipine. Our data, using a noninvasive technique, agreed with values of previous invasive evaluations. We suggest precaution in using verapamil and diltiazem in patients with BAV 1 degree and advise a selective use of calcium antagonist therapy.

Aged↗
PubMed1987

Amiodarone treatment in cardiac preexcitation syndrome: use of signal averaged electrocardiogram.

Amiodarone effectiveness to prevent reentrant arrhythmia in Wolff-Parkinson-White (WPW) syndrome is well known. Authors tried to evaluate the results of long-term therapy in a group of 11 patients (mean age 39 +/- years) suffering from WPW syndrome. Before amiodarone treatment, a conventional ECG and a high resolution ECG (a new noninvasive technique) were performed in order to define Hisian activity. After 50 days of therapy (600 mg daily for the first week, 400 mg daily for the second week, 200 mg daily for 5 days in the following period), a second recording revealed the evidence a a lengthening of PR segment (p less than 0.05) and a disappearance of delta wave (1 patient) and arrhythmia. Before treatment, His deflection was defined only in 2 patients. After amiodarone therapy the H-V time was clearly evaluated in 9 patients. Probably the drug has induced a lengthening of AV node refractoriness and primarily an increase of accessory pathway refractoriness.

Adolescent↗
PubMed1986

[Pulmonary carcinomatosis: a rare cause of acute cor pulmonale].

Five cases of neoplastic pulmonary embolism are reported in whom the clinical presentation was consistent with acute cor pulmonale. Perfusory lung scintigraphy was negative in all the cases. Four patients died within 7 days, one after 30 days from starting of symptoms. At autopsy in all the cases neoplastic diffuse embolization of pulmonary arteries was seen with or without thrombosis. In two cases lymphatic carcinosis was also evident. In the literature the majority of cases are reported to have a subacute clinical course as compared to the acute clinical evolution of our series. We suggest to keep in mind the diagnostic hypothesis of vascular pulmonary carcinosis in the cases of acute cor pulmonale with negative perfusory lung scintigraphy.

Acute Disease↗
PubMed1983

Cyclols, cyclodepsipeptides, and N-acyl-diketopiperazines from linear precursors. Synthesis and crystal structure of 10-membered cyclodepsipeptides.

In order to investigate the relative formation tendency of different tautomeric ring systems (cyclols, cyclodepsipeptides and corresponding N-acyl-diketopiperazines), two linear peptide precursors containing proline as C-terminal residue, have been synthesized and subjected to cyclizing conditions. Boc-Ser-Phe-Pro-ONp (I) gave three isomeric cyclic compounds: Boc-Ser-Phe-Pro- (IV), N-(Boc-Ser)-cyclo-(Phe-D-Pro) (III) and the corresponding aza-cyclol (II). Starting from Hyb-Phe-Pro-ONp (V) two epimeric N(3-hydroxybutyryl)diketopiperazines (VI) and (VII) and the corresponding 10-membered cyclodepsipeptide (VIII) could be isolated. Crystal and molecular structure of VIII is reported. Crystals of VIII are orthorhombic, P212121 with a = 9.684, b = 22.985, c = 7.841, z = 4. The two peptidic bonds are cis with omega values of 6.6 degrees and - 18.1 degrees, whereas the lactonic bond is of transoid type. The pyrrolidine ring has C2-C gamma-exo conformation.

Amino Acid Sequence↗