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Biomedical subjects

M Montalti

Publications and source records attributed to M Montalti.

7 recordsLinked to original sources
PubMed2006

Clinical value of multidetector CT coronary angiography as a preoperative screening test before non-coronary cardiac surgery.

OBJECTIVE: Myocardial scintigraphy and/or conventional angiography (CA) are often performed before cardiac surgery in an attempt to identify unsuspected coronary artery disease which might result in significant cardiac morbidity and mortality. Multidetector CT coronary angiography (MDCTCA) has a recognised high negative predictive value and may provide a non-invasive alternative in this subset of patients. The aim of this study was to evaluate the clinical value of MDCTCA as a preoperative screening test in candidates for non-coronary cardiac surgery. METHODS: 132 patients underwent MDCTCA (Somatom Sensation 16 Cardiac, Siemens) in the assessment of the cardiac risk profile before surgery. Coronary arteries were screened for > or = 50% stenosis. Patients without significant stenosis (Group 1) underwent surgery without any adjunctive screening tests while all patients with coronary lesions > or = 50% at MDCTCA (Group 2) underwent CA. RESULTS: 16 patients (12.1%) were excluded due to poor image quality. 72 patients without significant coronary stenosis at MDCTCA were submitted to surgery. 30 out of 36 patients with significant (> or = 50%) coronary stenosis at MDCTCA and CA underwent adjunctive bypass surgery or coronary angioplasty. In 8 patients, MDCTCA overestimated the severity of the coronary lesions (> 50% MDCTCA, < 50% CA). No severe cardiovascular perioperative events such as myocardial ischaemia, myocardial infarction or cardiac failure occurred in any patient in Group 1. CONCLUSIONS: MDCTCA seems to be effective as a preoperative screening test prior to non-coronary cardiac surgery. In this era of cost containment and optimal care of patients, MDCTCA is able to provide coronary vessel and ventricular function evaluation and may become the method of choice for the assessment of a cardiovascular risk profile prior to major surgery.

Biomarkers↗
PubMed2001

A strategy for the assembly of multiple porphyrin arrays based on the coordination chemistry of Ru-centered porphyrin pentamers.

An approach which employs pentameric porphyrin arrays as building blocks toward larger porphyrin arrays is described. Two flexible, and one relatively rigid, Ru-centered porphyrin pentamers (1-3) were synthesized and fully characterized. Their potential as building blocks toward larger porphyrin arrays has been studied via their coordination chemistry using bidentate and tetradentate ligands. DABCO (diazabicyclo[2.2.2]octane) can bind two monomeric porphyrins but was found to be too small to allow the complete formation of a 10-porphyrin array. On the other hand, titration of a larger bridging dipyridyl porphyrin ligand 17 (0.5 equiv) with 1 or 2 and tetrapyridyl ligand 18 (0.25 equiv) with 3 results in the formation of the 11-porphyrin and 21-porphyrin arrays, respectively, with the 21-porphyrin array containing porphyrins in three different metalation states. Changes in the chemical shift of the inner NH protons as well as the ortho- and meso-protons of the pyridyl groups of the porphyrin ligand clearly indicate the formation of large multiple porphyrin complexes. These studies demonstrate that by use of carefully designed building blocks and suitable bridging ligands, porphyrin arrays can be constructed with a dramatic increase in size in relatively few steps. Exploiting the fact that the strength of binding of pyridyl ligands is Ru > Zn > Ni, intra- vs intermolecular competition has been used to investigate aspects of the folding of the array. The photophysical properties of 3 are also described.

Magnetic Resonance Spectroscopy↗
PubMed2000

Photophysical and electrochemical characterisation of the interactions between components in neutral pi-associated

The electrochemical and photophysical properties of a variety of neutral pi-associated [2]catenanes have been explored by using cyclic voltammetry, absorption and luminescence spectrophotometry and the measurement of exited-state lifetimes. Several trends that could be correlated with interactions between the mechanically linked components of the structures were revealed from comparative study of catenane precursors, model compounds and the [2]catenanes themselves. Throughout, emphasis is placed on pair-wise comparisons between systems which differ in a single structural feature. Substitution in a catenane of a pyromellitic diimide unit by a naphthalene diimide yields more readily reduced derivatives, whose absorption spectra reveal charge transfer within the catenane to be a lower energy process of reduced intensity. Conversion of the butadiyne links within the diimide macrocycle of the catenanes to saturated chains results in an increase in both the energy and intensity of their charge-transfer bands; electrochemically these derivatives are all harder to reduce than the parent systems. Replacement of one of the electron-donating components of the catenanes with a less effective aromatic donor bearing a carboxy group also decreases the energy and intensity of the charge-transfer feature and is accompanied by a slightly more ready reduction. A sequence of reduction and translational events is proposed to explain the intriguing electrochemical behaviour of a catenane that contains one pyromellitic and one naphthalene diimide. For some systems the photophysical and electrochemical techniques, whilst exploring distinct physical phenomena, are shown to be in good agreement by comparison of shifts of electrochemical reduction waves with those of charge-transfer absorption features.

Journal Article↗
PubMed2000

Luminescent ruthenium(II) bipyridyl-phosphonic acid complexes: pH dependent photophysical behavior and quenching with divalent metal ions.

The synthesis, redox behavior, and photophysical properties of a series of Ru(II) bipyridyl complexes having diimine ligands with phosphonate and phosphonic acid substituents are presented. The phosphonate-containing ligands examined include diethyl 4-(2,2'-bipyrid-4-yl)benzylphosphonate (bpbzp), diethyl 4-(2,2'-bipyrid-4-yl)-phenylphosphonate (bppp), and 4,4'-(diethyl phosphonato)-2,2'-bipyridine (bpdp), and the [(bpy)2Ru(L)](PF6)2 complexes of both the diethyl phosphonate and the phosphonic acid were prepared. The Ru(III/II) potentials are more positive for the phosphonate complexes than for the phosphonic acids, and the first reduction is localized on the phosphonate-containing ligand for the bppp and bpdp complexes. The first reduction of the phosphonic acid complexes is at more negative potentials and cannot be distinguished from bpy reduction. For the bppp and bpdp complexes luminescence arises from a Ru(d pi)-->bpy-phosphonate (pi*) MLCT state; the phosphonic acid complexes luminescence at higher energies from a MLCT state not clearly isolated on one ligand. Iron(III) and copper(II) complex with and very efficiently quench the luminescence of all the phosphonic acid complexes in nonaqueous solvents. The quenching mechanism is discussed on the basis of luminescence decay and picosecond transient absorption measurements.

Journal Article↗
PubMedDate not supplied

Respiratory risks in tunnel construction workers.

Respiratory diseases are frequent in tunnel construction workers. A group of 144 subjects randomly selected from the population of 2516 workers engaged in the construction of the railway tunnel under the Appennine Mountains, from Bologna to Firenze was investigated. A group of 69 males comparable for age, living area and habits was studied as a control group. Assessment of air pollutants (NO, NO2, SO2, total dust, silica %) was carried out by means of fixed monitoring stations as well as personal monitors. All the subjects included in the study were examined with a standardised protocol which included physical examination, lung function tests (before and after shift work) and a questionnaire to college respiratory symptoms. Low concentrations of environmental pollutants were evidenced. Significantly lower values of FEV1 and PEF were determined in the worker group pared to controls. A significant decrease in respiratory parameters was shown after shift work. Variables capable of influencing the decrease in parameters include smoking habits, work activity, presence of cough and expectoration, period of the year (spirometries resulted worse in the winter time). Significantly lower values of FEV1 and PEF were evidenced in the workers compared to controls. In spite of the present low work environmental exposure conditions, some physiologic parameters appear altered in tunnel construction workers. This may depend on a variety of noxious agents present in the working environment.

Adult↗