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Biomedical subjects

M Ferrari

Publications and source records attributed to M Ferrari.

At least 37 records · Page 2Linked to original sources
PubMed1992

Protective effects of the Hemopump left ventricular assist device in experimental cardiogenic shock.

The efficacy of the new cable-driven rotating left ventricular assist device Hemopump in cardiogenic shock was examined in experiments with adult sheep (n = 14; body weight 50-71 kg). Shock was induced by high frequency ventricular pacing. Aortic, pulmonary, central venous and left ventricular pressures as well as electromagnetic measurements of coronary blood flow were recorded continuously; cardiac output was measured by thermodilution technique. Blood samples for determination of oxygen content, electrolytes and lactate were taken under control conditions, in shock, and during pump intervention at different levels of pump speed. Vascular resistance, total body and myocardial oxygen consumption as well as myocardial uptake and release of lactate were calculated. High frequency pacing led to a significant decrease in cardiac output (from 3.8 +/- 0.8 to 2.2 +/- 1.6 l/min), mean aortic pressure (89.1 +/- 14.4 to 47.6 +/- 7.2 mmHg), and total body oxygen consumption (2.6 +/- 0.3 to 1.4 +/- 0.7 ml/min per kg), as well as myocardial release of lactate (arterial coronary-venous difference of lactate: 0.27 +/- 0.26 to -0.32 +/- 0.72 mmol/l). Hemopump assist in this condition resulted in a significant increase in cardiac output (to 2.8 +/- 0.6 l/min), mean aortic pressure (to 65.6 +/- 13.9 mmHg), and myocardial perfusion pressure (from 25.5 +/- 11.0 to 59.0 +/- 14.7), and led to nearly normal total body oxygen consumption (2.5 +/- 0.7 ml/min per kg), a decrease in myocardial oxygen consumption (from 6.1 +/- 2.1 in shock, to 4.8 +/- 1.7 ml/min per 100 g), and to normal arterial coronary-venous difference of lactate (0.24 +/- 0.26 mmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Excimer laser intrastromal keratomileusis: case reports.

We report the results in six eyes on which we performed a new surgical method: intrastromal corneal excimer laser photoablation following lamellar corneal keratectomy with a microkeratome. The study was designed to evaluate the clinical and refractive efficacy of the procedure, to assess the behavior of the cornea following stromal photoablation, and to evaluate the relationship between the number of laser pulses and the decrease of myopia. The technique demonstrated an excellent corneal response to photoablation but a poor refractive predictability.

Adult↗
PubMed1992

Determination of lorajmine and its metabolite ajmaline in plasma and urine by a new high-performance liquid chromatographic method.

Lorajmine is a monochloroacetyl derivative of ajmaline with electrophysiological properties somewhat different from those of the compound of origin. Since lorajmine is rapidly hydrolyzed to ajmaline by plasma and tissue esterases, it is crucial to measure plasma levels of both drugs separately. A major problem in assaying lorajmine is its chemical instability in plasma both after blood sampling and during the extraction procedure. Furthermore, lorajmine (unlike ajmaline) is not fluorescent and has a very low UV absorbance, so the standard detectors for high-performance liquid chromatography cannot be used. We describe a new method that solves the problems of instability and sensitivity. Plasma esterases are first blocked pharmacologically (neostigmine); ajmaline is then measured by direct on-column injection of samples. Last, lorajmine is completely converted to ajmaline, extracted, and measured with a fluorescence detector. The molar concentration of ajmaline obtained in the last step, minus that found by direct injection, gives the concentration of lorajmine. Some examples of pharmacokinetic applications are also given.

Administration, Oral↗
PubMed1992

Effects of pinacidil on guinea-pig isolated perfused heart with particular reference to the proarrhythmic effect.

1. The effects of pinacidil (10, 30, 50 microM) on contractility (+dP/dtmax), coronary perfusion pressure (cP), and ECG intervals (PR, QRS, QT) have been studied on constant-flow perfused guinea-pig hearts, driven at four frequencies (2.5, 3, 3.5, 4 Hz). 2. Pinacidil decreased +dP/dtmax, cP and the QT interval in a dose-dependent manner, whereas the PR interval was increased. QRS duration was not modified. All these effects were independent of driving frequency. Pinacidil decreased the interval from Q-wave to T-wave peak (QTpeak) to a greater extent than the QT interval, thus decreasing the QTpeak/QT ratio. This effect, unlike that on QT interval, was more evident at the highest frequency of stimulation. 3. In 4 out of 20 hearts treated with pinacidil sustained ventricular fibrillation (VF) occurred following a short run of premature ventricular beats (R on T phenomenon). 4. In separate experiments, an attempt to induce VF electrically was made at drug concentrations ranging from 10 microM to 100 microM (8 experiments for each concentration). In control conditions and at the lowest concentrations of pinacidil tested (10 microM) VF could never be induced; in the presence of 30 microM pinacidil VF was induced in 5 out of 8 experiments. Drug concentrations higher than 50 microM permitted the induction of VF in every case. 5. Although the concentrations of pinacidil producing ventricular fibrillation are 30-40 times higher than those found in patients under long term treatment with this agent, it is suggested that caution should be used in prescribing this drug, at least in patients suffering from myocardial ischaemia.

Animals↗
PubMed1992

Marginal leakage of a new adhesive restorative system: a preliminary in vivo investigation.

The efficacy of newly developed adhesive restorative materials is commonly described by in vitro test results such as bond strength and microleakage data. Due to the inconsistency often found between in vitro testing and in vivo performance, the purpose of the present investigation was to restore teeth scheduled for extraction in vivo with an experimental restorative bonding system and to evaluate the microleakage of the restorations by common laboratory techniques following extraction after 3 months of clinical service. Two restorations were placed in each of seven anterior teeth, one in the middle of the labial enamel portion and the other labially extending over the cementoenamel junction (CEJ). Six of the seven fillings completely surrounded by enamel showed no microleakage. However, two of the restorations crossing the CEJ revealed microleakage originating from the cervical margins. In spite of the small number of fillings assessed, the experimental enamel-dentin adhesive compound tested is preliminarily considered a promising new system.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1992

Effects of graded hypotension on cerebral blood flow, blood volume, and mean transit time in dogs.

This study tested the hypothesis that cerebral blood flow (CBF) is maintained by vasodilation, which manifests itself as a progressive increase in mean transit time (MTT) and cerebral blood volume (CBV) when cerebral perfusion pressure is reduced. Cerebral perfusion pressure was decreased in 10 pentobarbital-anesthetized dogs by controlled hemorrhage. Microsphere-determined CBF was autoregulated in all tested cerebral regions over the 40- to 130-mmHg cerebral perfusion pressure range but decreased by 50% at approximately 30 mmHg. MTT and CBV progressively and proportionately increased in the right parietal cerebral cortex over the 40- to 130-mmHg cerebral perfusion pressure range. Total hemoglobin content (Hb1), measured in the same area by an optical method, increased in parallel with the increases in CBV computed as the (CBF.MTT) product. At 30 mmHg cerebral perfusion pressure, CBV and Hb were still increased and MTT was disproportionately lengthened (690% of control). We conclude that within the autoregulatory range, CBF constancy is maintained by both increased CBV and MTT. Outside the autoregulatory range, substantial prolongation of the MTT occurs. When CBV is maximal, further reductions in cerebral perfusion pressure produce disproportionate increases in MTT that signal the loss of cerebral vascular dilatory hemodynamic reserve.

Animals↗
PubMed1992

[The short- and long-term results in heart surgery of the elderly].

We have studied retrospectively 106 patients aged 69 years or older (range 69 to 79) who underwent cardiac surgery between November 1986 and December 1989. The majority of patients (61%) were male. Coronary artery bypass surgery was performed in 59 patients, isolated valve replacement in 38 and combined valve replacement with coronary artery bypass surgery in 5. Two patients underwent ascending aorta replacement for aortic dissection and 2 ventricular aneurysmectomy and postinfarction ventricular septal defect repair. The mean postoperative hospital stay was 12 days. Ninety-one percent of patients underwent a primary elective operation and 9% required an emergency operation. Hospital mortality was 5% (n = 6). All hospital survivors were followed up by telephone contact (mean follow-up: 37 months) to determine presence or absence of chest pain, dyspnea, postoperative NYHA class and the overall effect of surgery on quality of life. There were 16 follow-up deaths; 5 were non cardiac. Follow-up study showed significant improvement in symptom status and quality of life (96%). We concluded that cardiac surgery in the elderly, although associated with increased operative risk, gives excellent relief of symptoms and good survival.

Aged↗
PubMed1992

The response of pregnant gilts previously given an inactivated preparation of porcine parvovirus (PPV) to challenge infection with a fully virulent PPV.

Eight 40-day pregnant gilts, previously treated with an adjuvanted-inactivated viral preparation (AIVP) obtained with a field strain of porcine parvovirus (PPV) together with 4 pregnant untreated controls, were subjected to challenge infection with a virulent strain of PPV at the 40th day of gestation. After challenge, all controls became febrile for 2 to 8 days, whereas only one gilt among those which had been treated with the AIVP experienced fever which lasted 4 days. Virus was consistently recovered from fecal swabs obtained from the controls and only sporadically from feces of AIVP-treated gilts. When the gilts were killed 53 days after challenge infection, no macroscopic lesions were found in any of the gilts in either groups, but fetal death was observed in the two groups of animals. However, the rate of dead fetuses was much higher among the control (70.5%) than among those from the AIVP-treated gilts (10.1%). Virus was recovered from 23 of the 24 dead fetuses in the control group and only from 3 among the 8 dead fetuses which were reported for the AIVP-treated gilts.

Acrylic Resins↗
PubMed1992

Measurement of enamel thickness in relation to reduction for etched laminate veneers.

The etched porcelain laminate veneer is a new conservative treatment that offers a solution to fractured, discolored, and worn anterior teeth. Preparation of enamel should be 0.5 mm to give minimal porcelain thickness and to avoid an overcontoured restoration. At the same time, dentinal exposure is contraindicated, because resin bonds better with enamel than with dentin. One hundred fourteen extracted teeth were measured at the gingival, middle, and incisal thirds. The resulting data reported on labial enamel thickness of anterior teeth may offer guidance in the preparation of laminate veneers.

Acid Etching, Dental↗
PubMed1992

Cement thickness and microleakage under metal-ceramic restorations with a facial butted margin: an in vivo investigation.

Ten metal-ceramic restorations with buccal porcelain butt margins and palatal metal beveled margins were fabricated for periodontally hopeless teeth. After cementation, the experimental crowns remained in the oral environment for 3 to 6 months; the teeth were then extracted and used for microscopic and microleakage evaluation. All ten crowns showed at least a small amount of microleakage, but adaptation of beveled margins proved to be superior to that of shoulder porcelain margins.

Cementation↗