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T Marino

Publications and source records attributed to T Marino.

15 recordsLinked to original sources
PubMed2007

On the copper(II) ion coordination by prion protein HGGGW pentapeptide model.

The interaction of the octapeptide domain of the prion protein with the transition-metal-ion Cu2+ was studied at the DFT level by using the HGGGW pentapeptide as a model to mimic the PHGGGWGQ octarepeat sequence. Ten complexes, in which the metal ion exhibits different coordinations, were considered. Our results indicate that the lowest-energy structure is characterized by a tetracoordinated metal center and that this tendency of the ion to assume the square planar geometry is strong enough to prevent the addition of a further water molecule in its coordination sphere. The role of tryptophan was found to cause a lowering of the system energy due to the stabilizing effect of the electrostatic interaction between the Trp aromatic indole and histidine imidazole rings.

Circular Dichroism↗
PubMed2005

Interaction of cysteine with Cu2+ and group IIb (Zn2+, Cd2+, Hg2+) metal cations: a theoretical study.

The structure and energetics of complexes obtained upon interaction between cysteine and Zn2+, Cd2+, Hg2+ and Cu2+ cations were studied using quantum chemical density functional theory calculations with the 6-311++G** orbital basis set and relativistic pseudopotentials for the cations. Different coordination sites for metal ions on several cysteine conformers were considered. In their lowest energy complexes with the amino acid, the Zn2+ and Cd2+ cations appear to be three-coordinated to carbonyl oxygen, nitrogen and sulfur atoms, whereas the Cu2+ and Hg2+ ions are coordinated to both the carbonyl oxygen and sulfur atoms of one of the zwitterion forms of the amino acid. Bonds of metal cations with the coordination sites are mainly ionic except those established with sulfur, which show a small covalent character that become most significant when Cu2+ and Hg2+ are involved. The order of metal ion affinity proposed is Cu>Zn>Hg>Cd.

Cadmium↗
PubMed2001

Potential energy surfaces for the gas-phase interaction between alpha-alanine and alkali metal Ions (Li+, Na+, K+). A density functional study.

The conformations of alpha-alanine and those of the eight most stable adducts that it forms with lithium, sodium, and potassium cations were studied by means of the density functional theory using the hybrid B3LYP exchange correlation potential and the 6-311++G basis set. Minima and transition states characterizing the energetic paths for the interaction of the three metal ions with the free amino acid were explored in detail, and the results show that they are almost the same in the cases of lithium and sodium ions. At the absolute minimum, the Li+ and Na+ cations appear to be contemporaneously linked to the carbonyl oxygen and nitrogen atoms of alpha-alanine. Slight differences were found for potassium; the most stable adduct has the cation coordinated to both oxygen atoms of carboxyl function. The influence of the low-energy conformers in the determination of the gas-phase absolute affinities is demonstrated.

Alanine↗
PubMed2001

Density functional computations of proton affinity and gas-phase basicity of proline.

The proton affinity and gas-phase basicity of proline were evaluated by using density functional theory coupling the B3-LYP hybrid functional with the extended 6--311++G** basis set. Cis and trans conformations of the carboxyl moiety for both exo and endo ring structures were considered for the neutral proline. The results show that the most stable structure of proline has the endo ring conformation with the carboxyl group in the cis position. The structure at the global minimum is stabilized by an intramolecular hydrogen bond. The nitrogen of the ring in the exo form is the preferred protonation site. The calculated proton affinity (924.3 kJ mol(-1)) and gas-phase basicity (894.4 kJ mol(-1)) are in very good agreement with the experimental counterparts.

Gases↗
PubMed2001

On the fragmentation pathway of the ionized enol of glycine in the gas phase.

Density functional and second-order many body perturbation approaches were used to compute the potential energy surface for the fragmentation of the ionized enol of glycine [H2NCH = C(OH)2]+* into water and aminoketene radical cation [H2N-HC = CO]+*. Two possible pathways were considered. The potential energy surfaces obtained are very similar and both predict the existence of a molecular complex in which the water is coordinated to the aminoketene moiety in two different fashions with a noticeable binding energy. The fragmentation is kinetically controlled by the step in which the molecular complex is formed from the most stable cation enol of glycine. Our quantum-mechanical data confirm the hypothesis that the ylide ion [H3NCHCOOH]+* is an intermediate in the water loss.

Journal Article↗
PubMed2001

The anesthetic management of triplet cesarean delivery: a retrospective case series of maternal outcomes.

UNLABELLED: Spinal anesthesia for the cesarean delivery of triplets is associated with an increased incidence of maternal hypotension and placental hypoperfusion. We performed a retrospective case series analysis between January 1992 and June 2000 to evaluate the effects of regional anesthetic techniques for cesarean delivery in triplet pregnancies on maternal and neonatal outcome. Spinal and epidural anesthesia were compared with respect to intraoperative hemodynamics and neonatal outcomes. Ninety-six triplet pregnancies were delivered by cesarean section, of which 91 received regional anesthesia. A statistically significant decrease in systolic blood pressure was demonstrated immediately after the induction of spinal as compared with epidural anesthesia. The total volume of IV crystalloid used was significantly larger in the Spinal Anesthesia group. The number of patients receiving more than 15 mg of ephedrine and the cumulative dose of ephedrine was significantly larger in the Spinal group compared with the Epidural group. There were no differences in the rate of perioperative complications between the Spinal and Epidural Anesthesia groups. Neonatal Apgar scores were similar in both groups. The data suggest that both epidural and spinal anesthesia for triplet cesarean delivery are safe techniques, but the latter is associated with a larger initial decrease in systolic blood pressure. This decreasing of systolic blood pressure, however, remained within the physiological range and did not seem to be clinically significant. The need for more crystalloid fluids and ephedrine should be anticipated when spinal anesthesia is used for these cases. IMPLICATIONS: A large retrospective case series of the effects of spinal and epidural anesthesia on maternal hemodynamic profile during cesarean delivery for triplet gestation was performed. Our findings suggest that spinal anesthesia results in outcomes comparable to epidural anesthesia for both mother and newborns.

Adult↗
PubMed2001

End-tidal carbon dioxide measurements as a prognostic indicator of outcome in cardiac arrest.

PURPOSE: To evaluate the use of end-tidal carbon dioxide values in predicting survival in cardiopulmonary arrest. BACKGROUND: The decision about when to terminate resuscitative efforts for patients with cardiopulmonary arrest is often subjective. End-tidal carbon dioxide values have been suggested as potential objective criteriafor making this decision. METHODS: This study was a cooperative effort of the St Louis chapter of the American Association of Critical-Care Nurses and its members and involved 6 hospitals and an air evacuation service. All adult patients who had a cardiopulmonary arrest were eligiblefor the study. Once a patient with cardiac arrest was intubated, end-tidal carbon dioxide and cardiac rhythms were measured and recorded every 5 minutes for 20 minutes or until resuscitation efforts were terminated. Patients' survival at the time of the arrest, survival 24 hours after the arrest, and discharge status were followed up. RESULTS: A total of 127 patients were enrolled in the study. All but 1 patient with end-tidal carbon dioxide values less than 10 mm Hg died before discharge. End-tidal carbon dioxide values greater than 10 mm Hg were associated with various degrees of survival. Overall survival to discharge was less than 14%, regardless of the end-tidal carbon dioxide value. CONCLUSION: Measurements of end-tidal carbon dioxide can be used to accurately predict nonsurvival of patients with cardiopulmonary arrest. End-tidal carbon dioxide levels should be monitored during cardiopulmonary arrest and should be considered a useful prognostic value for determining the outcome of resuscitative efforts.

Capnography↗
PubMed2000

Isolated clubfoot diagnosed prenatally: is karyotyping indicated?

OBJECTIVE: To evaluate the appropriateness of fetal karyotyping after prenatal sonographic diagnosis of isolated unilateral or bilateral clubfoot. METHODS: We retrospectively reviewed a database of fetal abnormalities diagnosed by ultrasound at a single tertiary referral center from July 1994 to March 1999 for cases of unilateral or bilateral clubfoot. Fetuses who had additional anomalies diagnosed prenatally, after targeted sonographic fetal anatomy surveys, were excluded. Outcome results included fetal karyotype diagnosed by amniocentesis, or newborn physical examination by a pediatrician. RESULTS: During the 5-year period, 5,731 fetal abnormalities were diagnosed from more than 27,000 targeted prenatal ultrasound examinations. There were 51 cases of isolated clubfoot. The mean maternal age at diagnosis was 30.5 years. The mean gestational age at diagnosis was 21.6 weeks. Twenty-three of the women (45%) were at increased risk of fetal aneuploidy, on the basis of advanced maternal age or abnormal maternal serum screening. Six women (12%) had positive family histories of clubfoot; however, no cases of aneuploidy were found by fetal karyotype evaluation or newborn physical examination. All cases of clubfoot diagnosed prenatally were confirmed at newborn physical examination, and no additional malformations were detected. CONCLUSION: After prenatal diagnosis of isolated unilateral or bilateral clubfoot, there appeared to be no indication to offer karyotyping, provided that a detailed sonographic fetal anatomy survey was normal and there were no additional indications for invasive prenatal diagnoses.

Adult↗
PubMed2000

Gas-phase metal ion (Li+, Na+, Cu+) affinities of glycine and alanine.

The gas-phase metal affinities of glycine and alanine for Li+, Na+ and Cu+ ions have been determined theoretically employing the hybrid B3LYP exchange-correlation functional and using extended basis sets. All computations indicate that the metal ion affinity (MIA) decreases on going from Cu+ to Li+ and Na+ for both the considered amino acids. The absolute MIA values are close to the experimental counterparts with the exception of lithium for which a deviation of about 7 kcal/mol at the B3LYP level is obtained. The optimized structures indicate that Li+, Na+ and Cu+ prefer a bidentate coordination, bonding with both nitrogen and oxygen atoms of amino acids.

Alanine↗
PubMed1997

A study of ruptured tubal ectopic pregnancy.

OBJECTIVE: Ectopic pregnancy continues to be a leading cause of maternal morbidity and of reduced childbearing potential among women of reproductive age. Because of tubal rupture it is still the main cause of pregnancy-related death during the first trimester. The purpose of our study was to evaluate factors that may predispose a woman to rupture of a tubal ectopic pregnancy. METHODS: In this retrospective study of 693 ectopic pregnancies from three McGill University teaching hospitals, we compared risk factors, preoperative ultrasound, and serum hCG levels between cases with ruptured and unruptured tubal ectopic pregnancy. RESULTS: The age and the number of pregnancies among the two groups of women were similar. The gestational age of women with an unruptured tube was 6.9 +/- 1.9 weeks, and of those with a ruptured tube, the gestational age was 7.2 +/- 2.2 weeks. Tubal rupture was encountered more often in women with at least one child than in childless women. History of ectopic pregnancy was found in 35% of women with an unruptured tubal pregnancy and in 26% of those with a ruptured tube. Serum hCG levels at the time of treatment were not significantly different among the two groups of women. Eleven percent of women with a ruptured tube had serum beta-hCG levels of less that 100 IU/L. CONCLUSION: Tubal rupture is encountered more often in women with no history of ectopic pregnancy and in those with at least one child. This suggests that ectopic pregnancy is less suspected in these women. Tubal rupture is encountered less often in ampullary pregnancy and in small ectopic pregnancies. There is no correlation between serum beta-hCG levels and tubal rupture, and rupture can occur even when serum beta-hCG levels are very low.

Adult↗
PubMed1995

Conformational behaviour of the antineoplastic peptide dolastatin-10 and of two mutated derivatives.

The three-dimensional structure of dolastatin-10, an extremely potent cytostatic and antineoplastic peptide extracted from the mollusc Dolabella auricularia, has not yet been fully characterized in an experimental way. By means of a systematic conformational search of the natural peptide and of two mutated analogs, carried out both in vacuo and in aqueous solution, the present work allows to obtain insights into the conformational preferences of this remarkable compound. In addition, the ability to form intra- and intermolecular H-bonds as a function both of the sequence and of the conformation is discussed. The search for the best molecular conformations has been carried out using a molecular mechanics approach, based on the CVFF potential. Dolastatin-10 contains some unusual amino acids for which no experimental structural data are available. In order to check the reliability of the CVFF potential in predicting structures of such nonconventional amino acids, geometry optimizations have been carried out using the ab initio Hartree-Fock procedure. The CVFF parameterization is found to be adequate also for nonconventional amino acids.

Amino Acids↗
PubMedDate not supplied

Theoretical comparison between structural and dynamical features of Dolastatins 11 and 12 antineoplastic depsipeptides.

Molecular mechanics (MM) and dynamics (MD) calculations in vacuo and in water have been performed for the natural cyclodepsipeptides Dolastatins 11 and 12 isolated from the sea hare Dolabella auricularia. The analysis of the MD trajectories for the two systems can give useful insight on the backbone structural features, side-chain and peptide-water interactions as well as on the inter- and intra-molecular hydrogen bonds. A comparison between the selected and analysed lowest energy isomers shows the different conformational behaviour of the compounds. Finally, with the aim to ascertain a structure-activity relationship for the two peptides, the interactions of both Dolastatins with water, generic hydrophobic environment, magnesium and calcium ions have been investigated by means of the GRID program.

Depsipeptides↗