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Biomedical subjects

M Ferrari

Publications and source records attributed to M Ferrari.

At least 163 records · Page 9Linked to original sources
PubMed1998

Optimized detection of DNA point mutations by double gradient denaturing gradient gel electrophoresis.

Denaturing gradient gel electrophoresis displays the highest detection rate among mutation scanning methods. In classical denaturing gradient gel electrophoresis the denaturant gradient range and migration times vary for every amplicon to be scanned, greatly affecting the routine application of the method. As an alternative, we developed double gradient denaturing gradient gel electrophoresis where a gradient of pore size is superimposed over the denaturing one, allowing maintenance of the zone-sharpening effect even over prolonged time runs, and adoption of identical run time conditions for all fragments analyzed. Here double gradient denaturing gradient gel electrophoresis has been applied to the analysis of a number of point mutations and polymorphisms located in several exons of three different genes, the cystic fibrosis transmembrane conductance regulator, the beta-globin and the p53 genes.

Cystic Fibrosis Transmembrane Conductance Regulato↗
PubMed1998

[Radiation protection in the use of tracers in radioguided breast surgery].

PURPOSE: Recent techniques in nuclear medicine have permitted to implement new procedures useful in surgery. Among these, the procedures for locating sentinel lymph nodes and nonpalpable breast lesions are of great interest. The protocols for the location of the sentinel lymph node and for the radioguided location of occult lesions developed at the European Institute of Oncology (IEO, Milan) are based on the administration of radiopharmaceuticals labelled with Technetium-99m (99mTc). We evaluated the dosimetric data relative to patients and hospital personnel to assess whether specific radiation protection procedures are needed. MATERIAL AND METHODS: Fifty patients with nonpalpable breast lesions and 50 patients with suspected lymph node involvement were enrolled in this study. All the patients underwent surgery the day after in-loco administration of the radiopharmaceutical (11 MBq of 99mTc). The absorbed dose to the hospital personnel was estimated from the air kerma rate measured by ionization chamber at different distances from the patients at 0 and 16 hours after the radiopharmaceutical administration. In order to evaluate radiation protection for patients, absorbed doses were measured positioning thermoluminescent dosimeters on the patient's skin for about 16 hours. In the operating room, activity was measured on some excised tissues (lymph nodes and tumors) and on surgical instruments. RESULTS: Absorbed doses were very low for the clinical staff also in case of prolonged patient assistance. After 100 cases, the surgeon mean absorbed dose to the hands and mean effective dose were .45 mGy and .09 mGy, respectively. These values correspond to 1% of the annual dose limit to the hands and to 10% of the annual equivalent effective dose recommended for the population (ICRP 60 and law by decree 230/95). The absorbed dose to healthy tissues of the patients were lower than 1 mGy (mean values: contralateral breast: .9 mGy; abdomen .45 mGy). The mean activity detected in the excised tissues was 9 kBq and 900 kBq in the sentinel lymph nodes and in the tumor lesions (injection site), respectively. The activity detected on the surgical instruments, higher on gauzes (< 100 kBq), was negligible. CONCLUSIONS: From the radiation protection point of view, the data support the validity of our protocols. Absorbed doses to the hospital personnel are low and require neither a radiation protection control nor a classification of exposed workers as classes A or B. Special containers for radioactive wastes are necessary in the administration room but not in the operating room, where the levels of possible contamination are negligible.

Breast Neoplasms↗
PubMed1998

Identification and quantification of intrinsic optical contrast for near-infrared mammography.

Near-infrared spectroscopy has been used to quantify the composition of healthy female breast tissue in vivo. By collecting transillumination spectra in the wavelength range 680-1100 nm at 7-9 positions on the breasts of five female volunteers, an attempt was made to quantify the intra- and intersubject variability of breast composition. The dominant absorbers are water, lipids and hemoglobin. Hemoglobin concentration in the breast is substantially lower than that in the brain or muscle (less than 10 microM). The measured deoxyhemoglobin concentration can vary by up to 100% between different positions on the same breast. Water and lipid concentrations can show similar variability. Phantom and simulation studies demonstrate that this variability is not due to the effects of tissue boundaries on the measurements. The low hemoglobin concentration implies that optical breast imaging should be performed at wavelengths below about 850 nm to ensure that the image contrast comes predominantly from hemoglobin. Intrasubject variability could have implications for the ability of optical imaging to discern tumors from background contrast variations.

Adult↗
PubMed1998

Rapid capillary zone electrophoresis in isoelectric histidine buffer: high resolution of the poly-T tract allelic variants in intron 8 of the CFTR gene.

The poly-T tract in intron 8 of the cystic fibrosis conductance transmembrane regulator (CFTR) gene exists in three variants, 5T, 7T, and 9T. The 7T and 9T variants generate a predominantly normal transcript, whereas the 5T variant engenders an anomalous product. The analysis of the poly-T tract is assuming increasing relevance, both to assess the implication of the CFTR gene in congenital bilateral absence of the vas deferens and to evaluate genotype-phenotype correlation in cystic fibrosis. Mapping of the poly-T tract has been performed by cumbersome and time-consuming methodologies. Capillary zone electrophoresis, combined with laser-induced fluorescence detection, was introduced for a rapid separation of the poly-T tract amplified products. As separation buffer, we adopted 200 mmol/L histidine (pH = pI = 7.6), and the capillary was filled with 10% polyacrylamide, allowing separations in less than 10 min. Capillary zone electrophoresis results were in perfect agreement with dot-blot analysis.

Alleles↗
PubMed1998

An undetected burden of asthma in Italy: the relationship between clinical and epidemiological diagnosis of asthma.

This study aimed to compare questions and tests used in asthma epidemiology with clinical diagnosis of current asthma and to assess the extent of undiagnosed asthma in Italy. Thus, 811 attenders to the second stage of the European Community Respiratory Health Survey were classified by panels of respiratory physicians as current asthmatics or not. Among those with a clinical diagnosis of asthma (n=105), 69% reported current wheezing and 68% asthma in their lifetime (ever asthma), while asthma attacks in the previous year and/or current treatment for asthma (self-reported current asthma) were mentioned by only 37%. Thirty two per cent did not mention asthma at any time, but nevertheless presented a rate of hospitalization close to that of people with self-reported current asthma. On the other hand, almost no subjects labelled nonasthmatics by clinicians (n=706) presented self-reported current asthma (99.7%), while some reported ever asthma (5%) or current wheezing (9%). A model simulation showed that, in its usual range (0-15%), asthma prevalence is markedly overestimated by the question on wheezing and underestimated by the questions on self-reported current asthma, with respect to clinical judgement. Prevalence estimates close to those obtained by clinical judgement were achieved by combining asthma-like symptoms in the previous year with the results of lung function and allergological tests, but especially by using the single question on ever asthma. In conclusion, the present results suggest that the question on ever asthma gives prevalence estimates close to those obtained by clinical judgement and that asthma is greatly underdiagnosed in Italy.

Adult↗
PubMed1998

Evaluation of potential factors affecting the measurement of cerebrovascular reactivity by near-infrared spectroscopy.

1.Near-infrared (IR) spectroscopy is based on the relative transparency of skin, skull and brain to the light in the near-IR region (700-1100 nm) and on the oxygen-dependent tissue absorption changes of haemoglobin.2. We evaluated the most relevant factors (reproducibility, venous return, age and sex) that might affect reliability of near-IR spectroscopy to test CO2 cerebrovascular reactivity.3.Thirty-four healthy volunteers were enrolled in the study. The protocol consisted of a 3-min baseline, a 3-min hypercapnia (5% CO2 in air) and a 2-min recovery. Transcranial Doppler sonography measurements were simultaneously performed. The CO2 reactivity test was repeated on 27 subjects after 1 h to assess reproducibility. CO2 reactivity was also evaluated at different body positions (supine, 35 degrees Trendelenburg and 35 degrees reverse Trendelenburg), and over a gradual increase of the inspired CO2.4. Changes in near-IR spectroscopy and transcranial Doppler sonography parameters were significantly correlated with variations of end-tidal CO2 (P<0.005). A significant correlation between the reactivity indexes of near-IR spectroscopy parameters and flow velocity was also found (P<0.01). A high reproducibility was also found for deoxyhaemoglobin (rI=0.76), oxyhaemoglobin (rI=0.68) and flow velocity (rI=0.60) reactivity indexes. No significant differences between the reactivity indexes of different body positions were found (P>0.05). The reactivity index of oxyhaemoglobin and deoxyhaemoglobin decreased (P<0.05) and increased (P<0.01) with age respectively.5. We found that near-IR spectroscopy is a reliable and reproducible method for the evaluation of cerebrovascular reactivity and might be considered, after appropriate validation, for the assessment of patients with cerebrovascular disease.

Adolescent↗
PubMed1998

Handling characteristics of resin composites in posterior teeth.

In the last 10 years, tremendous improvements in strength and shade selection for resin composites have been achieved. Also, a new generation of enamel-dentin bonding systems has been developed, and patient expectations of esthetic treatment have risen. Several techniques are available for restoring posterior teeth. When a caries lesion is limited, a direct esthetic restoration is indicated. Essential elements for obtaining good, long-term clinical results for direct esthetic restorations of posterior teeth are: (1) cavity preparation; (2) knowledge of the characteristics of the three dental substrates; (3) rubber dam use and matrix and wedge placement; (4) correct use of the enamel-dentin bonding system; (5) proper selection of the resin composite material; (6) use of the multilayering technique; (7) finishing and polishing procedures; and (8) maintenance of the restoration.

Acid Etching, Dental↗
PubMed1998

Prevalence of asthma and asthma-like symptoms in an adult population sample from Verona. ECRHS Verona. European Community Respiratory Health Survey.

The aim of the study was to assess the prevalence of asthma and asthma-like symptoms in the general population of Verona. A screening questionnaire, with seven questions on respiratory symptoms, was sent by mail to 3000 randomly selected subjects, aged 20-44 yrs. After three subsequent mailings, nonresponders were interviewed by telephone. The overall response rate was 92%. At least one respiratory symptom was reported by 44% subjects. The prevalence of the most frequent symptoms differed according to the type of contact: early respondents (i.e. those who responded by mail) were more likely to report symptoms than late respondents (i.e. those who were interviewed by telephone). Wheezing was reported by 11.3% of males and 8.0% of females (p < 0.01). The allergic rhinitis and hay-fever prevalence was 16.9% with no differences owing to sex or age. The prevalence of an "episode of asthma" (defined as a self-reported attack of asthma or treatment for asthma) and of "current asthma" (defined as a self-reported attack of asthma, treatment for asthma or wheezing other than due to a cold with dyspnoea in the last 12 months) was 4.1 and 4.7%, respectively. No differences were found on the basis of age and sex. The prevalence of asthma was greater in urban (5.0%) than in suburban (2.7%) areas (p < 0.05), where lower pollution levels were registered. The greater prevalence in urban areas suggests that some factors related to the urban environment could play a role in the development of asthma and asthma-like disorders.

Adult↗
PubMed1997

Near infrared absorption spectra of human deoxy- and oxyhaemoglobin in the temperature range 20-40 degrees C.

Temperature-dependent spectral changes of human haemoglobin A (HbA) derivatives were investigated in the range 20-40 degrees C. The intensity of the deoxy-HbA decreased by 3-3.5%, while that of oxy- and met-HbA by less than 1%, when the temperature increased from 20 degrees to 40 degrees C. The present findings can be employed to improve the algorithms used in in vivo near infrared spectroscopy.

Hemoglobins↗
PubMed1997

Oxidative metabolism in muscle.

Oxidative metabolism is the dominant source of energy for skeletal muscle. Near-infrared spectroscopy allows the non-invasive measurement of local oxygenation, blood flow and oxygen consumption. Although several muscle studies have been made using various near-infrared optical techniques, it is still difficult to interpret the local muscle metabolism properly. The main findings of near-infrared spectroscopy muscle studies in human physiology and clinical medicine are summarized. The advantages and problems of near-infrared spectroscopy measurements, in resting and exercising skeletal muscles studies, are discussed through some representative examples.

Energy Metabolism↗
PubMed1997

Adsorption Kinetics of Alkylphosphine Oxides at Water/Hexane Interface

A pendant drop technique has been used to study the adsorption of a nonionic surfactant, an alkyldimethylphosphine oxide (C13DMPO), at the water/hexane interface. The measured interfacial tensions exhibit a steep initial decrease, pass through a minimum, and then level off at a value which depends on the initial surfactant concentration in the drop. This time dependence of the interfacial tension can be interpreted by an adsorption with a subsequent transfer of the surfactant into the second bulk phase, hexane. Measurements of the distribution coefficient show that the solubility of C13DMPO is much higher in hexane than in water. A qualitative model is proposed which describes the observed dynamic interfacial tensions.

Journal Article↗
PubMed1997

Adsorption Kinetics of Alkylphosphine Oxides at Water/Hexane Interface

A theoretical model is presented to describe the adsorption of surfactant molecules at the water/oil interface for the case when transport across the interface must be considered due to the solubility of the surfactant in both liquid phases (aqueous solution drop in an oil phase). The theory is based on a diffusion-controlled adsorption model and a numerical difference scheme is used to solve the problem for closed finite systems. By simulating adsorption-desorption processes, the influence of the geometrical and thermodynamic parameters on the dynamic adsorption behavior is studied. In particular, the effects of the volume ratio, surfactant concentration, diffusion coefficients, and distribution coefficient on the process are analyzed. The model allows quantitative interpretation of the experimental data obtained for an alkyldimethylphosphine oxide at the water/hexane interface. The interfacial tension signals, presenting a minimum under some conditions, are fitted by the theoretical curves.

Journal Article↗
PubMed1997

Modulation of neurotransmitter release by opioid mu- and kappa-receptors from adrenergic terminals in the myenteric plexus of the guinea-pig colon: effect of alpha 2-autoreceptor blockade.

We have studied the effect of [D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin (DAMGO, opioid mu-receptor agonist) and ICI-204,448 (kappa-receptor agonist) on endogenous noradrenaline release in the guinea-pig isolated distal colon. DAMGO enhances noradrenaline over-flow and this effect is antagonized by naloxone (pIC50 = 10.27) and nor-binaltorphimine (pIC50 = 7.97), and concentration-dependently turned into inhibition by yohimbine. ICI-204,448 inhibits noradrenaline overflow and is antagonized by naloxone (pIC50 = 9.38) and nor-binaltorphimine (pIC50 = 10.48), but is not affected by yohimbine. Evidence is thus given that mu- and kappa-opioid receptors modulate noradrenaline release in the guinea-pig colon. Modifications by yohimbine of the effect of DAMGO indicate the existence of a functional relationship between mu-receptors and alpha(2)-autoreceptors in this model.

Adrenergic alpha-2 Receptor Antagonists↗
PubMed1997

Evaluation of an active coronary perfusion balloon device using Doppler flow wire during PTCA.

The aim of this study was to assess whether active coronary perfusion catheters (APC) can provide a sufficient coronary flow in large caliber vessels during balloon inflation. To prevent myocardial ischemia during PTCA, these APC may be employed. However, it is as yet unknown whether the active flow rate of these devices approaches the flow rate prior to PTCA during balloon inflation. Therefore, we measured the efficacy of the APC during balloon inflation in vessels supplying a large amount of myocardium. In 12 patients (1 female, 11 males, 53 +/- 12.6 yr) with stenosed vessels (average diameter 3.4 +/- 0.26 mm), the coronary flow velocity was measured using a 0.014" Doppler guidewire, which was placed distally bypassing the balloon of the APC. The active perfusion balloon catheter was advanced through a 7F guiding catheter along a 0.014" guidewire. After removal of the guidewire, arterial blood being withdrawn from the side port of the femoral angioplasty sheath was pumped through the catheter to the distal coronary vessel. The perfusion volumes of the pump were set to different levels between 30 to 60 ml/min. Intracoronary flow rate was calculated by the angiographically assessed vessel luminal area [symbol: see text] average peak velocity [symbol: see text] 0.5. The mean coronary flow rate prior to PTCA was 43 +/- 17.7 ml/min. Maximum flow during PTCA was 55 +/- 19.6 ml/min. We found a good correlation between the preset external pump rate and the coronary flow in situ (r = 0.92). Pre-PTCA flow rates were achieved in 11 of 12 patients (92%) during balloon inflation. No relevant decrease in the arterial pressure occurred during dilation times of 4.6 +/- 1.63 min. Only two patients showed significant ECG changes during these balloon inflations. After an average follow-up period of 13 +/- 6.3 mo, only one patient (8%) had a significant re-stenosis requiring the implantation of a stent. The combination of intravascular Doppler velocity measurements with quantitative coronary angiography offers the opportunity of exact online flow registration during angioplasty. Using APC, It is possible to maintain a sufficient coronary flow in the distal vessel during balloon inflation even in large vessels. Therefore, as compared with mechanical circulatory assist devices, coronary assist by APC is a little invasive, but according to our measurements it might be a sufficient tool for performing PTCA also in high-risk patients.

Adult↗
PubMed1997

Lack of association of DMB polymorphism with insulin-dependent diabetes.

Considerable evidence exists that the genes coding for the HLA class II DQ molecules in the MHC region are major contributors to genetic susceptibility in insulin-dependent diabetes. Located centromeric to the DQ loci are the genes encoding DMA and DMB, two class II-like molecules which play an essential role in the pathway leading to antigen presentation by HLA class II. In this study we have examined the distribution of the DMB allele and studied HLA DQA1-DQB1-TAP2-DMB haplotypes in 52 IDDM families and 65 un-related controls. DMB allele frequencies in IDDM and control subjects were not significantly different. DMB*0101 was present in 85% of patients vs. 76% of controls, DMB*0102 in 12 vs. 17%, DMB*0103 in 3 vs. 5%, DMB*0104 in 0 vs. 2%. The IDDM-susceptible MHC DQA1-DQB1 haplotypes found by analysis of IDDM families were not associated with specific DMB alleles. We conclude that the described DMB polymorphisms are not associated with IDDM susceptibility and DMB genotyping is unlikely to improve the assessment of genetic risk for IDDM.

Alleles↗
PubMed1997

Adaptation of the QT interval to heart rate changes in isolated perfused guinea pig heart: influence of amiodarone and D-sotalol.

The inadequacy of the QT interval to shorten following heart rate increase is a feature of the inherited long QT syndrome and may have a role in the genesis of the typical arrhythmias associated with this syndrome (torsade des pointes). The aim of our study was to evaluate whether drugs that prolong the QT interval, such as amiodarone and D-sotalol, may also impair the ability of the QT interval to adapt to sudden heart rate changes. Experiments were carried out on isolated perfused guinea pig hearts (Langendorff preparation). Driving frequency was changed, in steps, every two minutes (Hz: 2.5-3-2.5-3.75-2.5-5-2.5), while epicardial ECG was continuously recorded on magnetic tape. QT interval was automatically measured by means of a beat-by-beat analysis program. D-sotalol was added to the perfusion medium at a concentration of 4 micrograms ml-1, while amiodarone was administered, before in vitro evaluation, for seven days (50 mg kg-1 per day, intraperitoneally). In control experiments two phases of QT adaptation were identified: an abrupt QT shortening at the first beat after frequency change (QT1), followed by a gradual, exponential QT shortening that reached a new steady state in about 1 min (half life: 13 sec). The electrical restitution curve (the relation between QT1 and the corresponding diastolic interval) had a rate constant of 57 +/- 8 ms. Neither drug changed the slow component of QT adaptation. However, both drugs increased the ability of QT to shorten upon premature stimulation: D-sotalol by increasing the rate constant of the restitution curve and amiodarone by decreasing the y-intercept. Our results indicate that D-sotalol and amiodarone do not impair QT shortening during tachycardia but, on the contrary, they may favour QT adaptation, thus reducing the likelihood of the potentially lethal 'R on T phenomenon'. This may be an additional mechanism by which these drugs can exert their antifibrillatory action.

Adaptation, Physiological↗