Biomedical subjects
Publications and source records attributed to M Tomassetti.
Enzyme sensors for urea and creatinine were developed by coupling an ammonia gas-diffusion electrode with triacetate cellulose membranes entrapping urease or creatinine deiminase enzymes. Satisfactory results were obtained by using these sensors both in standard solutions and in authentic biological matrices.
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Forty mothers undergoing elective Caesarean section under general anaesthesia were allocated randomly to receive either propofol 2.8 mg kg-1 (n = 20) or thiopentone 5 mg kg-1 (n = 20) for induction of anaesthesia. Twenty neonates delivered by uncomplicated vaginal delivery were evaluated also as unmedicated controls. Neurobehavioural examinations were carried out at 1, 4 and 24 h after delivery. Infants in the propofol group had lower Apgar scores at 1 and 5 min; 25% of them had muscular hypotonus at 5 min. This hypotonus was not noted during the Early Neonatal Neurobehavioural Scale (ENNS) examination. Newborn children examined 1 h after birth, after maternal anaesthesia with propofol, showed a depression in alert state, pinprick and placing reflexes, and mean decremental count in Moro and light. There was a generalized irritability in 25% of them. This depression was not observed at 4 h.
A PVC (polyvinychloride) ion selective electrode, employing benzyldimethyl-cetylammoniumbenzylpenicillin as sensor, was prepared, characterized and applied to the analysis of commercially available formulations containing benzylpenicillin and other antibiotics of the penicillin or cephalosporin group. The results are compared with those obtained by using the corresponding liquid membrane electrode.
Two new polymeric membrane electrodes selective to cholate and to benzylpenicillinate, based respectively on PVC membranes containing polybenzyl-propargilamine as conductor polymer and benzyldimethylcethylammonium-cholate, or -benzylpenicillinate as exchangers, have been prepared, and applied to the determination of cholic acids, anionic surfactants and antibiotics. Results are compared with those ones obtained by analogous PVC sensors and liquid membrane sensors, previously described.
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A new rapid and direct method for the determination of choline-containing phospholipids in the amniotic fluid is proposed. The determination is performed by an amperometric-enzymatic method. The correlation with an enzymatic-spectrophotometric method, already published, is also considered.
A cholate-selective liquid membrane electrode has been applied to the determination of the pool of cholic acids in human bile. Pretreatment of the sample was necessary for reliable potentiometric determination; different procedures were tried for pretreatment of human bile.
A simple method for direct determination both of choline and lecithin (phosphatidylcholine) in human bile and blood sera was developed. An enzyme electrode, based on immobilized choline oxidase on nylon net and an oxygen Clark electrode was assembled. Phosphatidylcholine can be determined by use of phospholipase D as hydrolyzing agent. Reliable results were obtained in the case of determination of lecithin and choline in bile samples.
The two most commonly used spectrometric methods for the determination of the phosphorus content of human bile are compared. The optimum experimental conditions are studied, and the analytical characteristics of the two methods, using both standard samples and human bile, are evaluated. The methods are compared on the basis of their sensitivity, precision and accuracy, and the correlation between the two techniques demonstrated using fifteen samples of human bile. Data obtained by both methods have been used to calculate lithogenic index values.
A reliable cholesterol electrode was assembled with a Clark type oxygen electrode and cholesterol oxidase immobilised on a nylon net fixed on the electrode surface. Determination of free (unesterified) and total (esterified and unesterified) cholesterol in human bile samples was performed. Results were compared with the enzymatic-spectrophotometric procedure based on the Roeschlau method. The electrode has a usable life of more than two weeks, and more than 300 determinations could be performed. The CV values for free and total cholesterol in bile samples is 5-6%. The comparison between the proposed procedure and the spectrophotometric procedure is fair for the half of the results (delta less than 5%) and acceptable in the other half (delta less than 25%).
A potentiometric method based on phosphate precipitation with Pb2+ and on a lead ion selective electrode is applied to the determination of bile phosphates. The method is rapid and simple and does not require extensive sample pretreatment.
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Using a cellulosic material dating method recently proposed by three of the authors of the present article further applications to real samples are discussed. In the first instance, to wood samples, that is, to a type of sample for which the method was specifically developed but with the samples differing widely in age, and then to textile or paper samples. Of course in the latter two cases the results obtained are still quite preliminary, above all because of the difficulty of procuring certainly dated samples of this type.
A suitable enzyme sensor for the analysis of anticholinesterase compounds of pharmaceutical interest is described. It is based on the competitive inhibiting properties of these compounds on the enzyme butyrylcholinesterase and it is constituted by a hydrogen peroxide amperometric electrode modified by a superimposed Nylon membrane containing two chemically immobilized biological mediators (butyrylcholinesterase and choline oxidase). Some applications to the analysis of several pharmaceutical forms containing different compounds showing anticholinesterase activity are also reported and evaluated.
The direct determination of chlorocresol in n-hexane extracts of commercial ointments was successfully performed using an enzyme-amperometric probe for analysis of phenols and working in previously characterized and optimized non-aqueous solvents. The analytical data obtained were compared with those found by using classical HPLC or chemical spectrophotometric method for determination of phenols.