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Biomedical subjects

G Ferretti

Publications and source records attributed to G Ferretti.

At least 145 records · Page 8Linked to original sources
PubMed1997

Effect of aluminium ions on liposomal membranes as detected by Laurdan fluorescence.

We report here an investigation of the influence of aluminium on iron-induced peroxidation in brain model membranes. Laurdan fluorescence emission spectra and generalised polarisation measurements have been used to investigate how ferrous and aluminium ions can affect the phase components of phospholipid membranes. An increase in the generalised polarisation of oxidised liposomes with respect to controls has been observed, which reveals the presence of a less polar environment surrounding the probe that changes the properties of the bilayer. Aluminium has been shown to facilitate iron-mediated oxidation as detected from emission fluorescence spectra. However, no quantitative influence has been calculated relative to general polarisation and derived phase state determinations. The structural influence of aluminium on membranes may therefore be less significantly marked than initially expected.

2-Naphthylamine↗
PubMed1997

[Profound venous thrombosis and popliteal cyst: problems of differential diagnosis relative to the use of phleboscintigraphy. Description of a clinical case].

The following is the case report of M. G. a 68-year-old male carrier of polcythemia vera, a pathology in which the risk of thrombosis is increased. The patient presented clinically suspected deep venous thrombosis and a phleboscintigraphy confirmed the diagnosis. A real-time B-mode ultrasonography performed later instead demonstrated a popliteal cyst. The case report focuses on diagnostic methods in deep venous thrombosis and particular attention is paid to the role of phleboscintigraphy, of impedance plethysmography and of real time B-mode ultrasonography.

Aged↗
PubMed1997

[Giant thymic lipoma: anatomical, radiologic and clinical aspects].

We report the case of a 51-year-old man who presents with worsening dyspnea at exercise caused by a large thymic lipoma (6 kg). We present the clinical, radiological, and spiral CT scan features of this rare and benign tumor and correlate them with the pathologic findings.

Humans↗
PubMed1997

[Detection of renal artery stenoses by MRI with surface reconstruction. Value in patients with chronic renal failure].

Forty-three patients with renal artery stenoses were examined with time of flight MR angiography using maximum intensity projection and surface shaded rendering, and with digital substraction angiography. Sensitivity and specificity were 0.83 and 0.78 for main and secondary arteries, 0.87 and 0.84 for main arteries. In azotemic patients, the positive predictive value was estimated at 40%-70% and the negative predictive value at 95%-98%, while the prevalence of renal artery stenoses varied from 10% to 30%. These results validate MRI for the detection of renal artery stenoses in this population. Surface shaded display was more accurate than maximum intensity projection to reconstruct time of flight sequences and to grade renal artery stenoses.

Adult↗
PubMed1996

Initial isolated Takayasu's arteritis of the right pulmonary artery: MR appearance.

Takayasu's arteritis involves the pulmonary artery tree in more than 50% of the cases. Initial isolated involvement of the pulmonary artery by Takayasu's arteritis, however, is very rare. We report the case of a 34-year-old white woman who presented a clinical and radiographic pattern that mimicked an acute pulmonary embolism with pulmonary infarction. Pulmonary angiography showed stenosis lesions and occlusion of the right pulmonary artery tree. Magnetic resonance imaging demonstrated thickening of the pulmonary artery wall leading to the correct diagnosis.

Adult↗
PubMed1996

Detection of oncogene mutation from neoplastic colonic cells exfoliated in feces.

PURPOSE: Best chances of a cure from colorectal cancer are obtained before metastatic spread. Lack of specific tests allowing early diagnosis of the tumor accounts for investigation of gene alterations involved in carcinogenesis by a noninvasive method. In the present study, K-ras codons 12 and 13 mutations were studied in neoplastic cells shed from the bowel into the stool and those contained in the tumor and normal mucosa. Moreover, healthy patients and a few others with precancerous conditions were examined. METHODS: Stool, tumor, and mucosa samples were taken from 25 patients with colorectal adenocarcinoma. Stool and mucosa samples were obtained from 11 healthy patients, and stool, pathologic bowel tissue, and normal mucosa samples were obtained from 3 patients with adenoma (1) or ulcerative colitis (2). Polymerase chain reaction amplification and restriction enzyme analysis were performed. RESULTS: K-ras codon 12 mutations were detected in both tumor and stool samples of 10 cancer patients, and no gene alterations were observed in 14 patients. In one patient with a tumor, a mutation was shown in only the tumor tissue. The agreement rate in tumor and stool analysis was 96 percent. A normal pattern of K-ras codons 12 and 13 was observed in the bowel mucosa. All stool and mucosa samples from healthy patients were not altered in K-ras. Agreement was registered between samples taken from patients with preneoplastic lesions. CONCLUSIONS: These preliminary findings show a high rate of accuracy in the investigation of K-ras alterations in the colorectal cells shed into the feces, suggesting that such an approach could be used to study other gene alterations and, prospectively, to identify early colorectal cancers.

Aged↗
PubMed1996

Plasma membrane fluidity of keratinocytes of normal and psoriatic skin: a study using fluorescence anisotropy of trimethylammoniumdiphenylhexatriene (TMA-DPH).

The aim of this study was to investigate plasma membrane fluidity in human keratinocytes using fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its cationic derivative 1-[4-(trimethylamino)-phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH). Keratinocytes from normal or psoriatic skin were isolated using trypsin-EDTA or dispase. In keratinocytes isolated from normal skin, TMA-DPH anisotropy values were higher than those observed using DPH; the difference must be related to the different localization of the two probes. In fact, DPH in whole cells localizes in plasma as well as intracellular membranes, yielding an average value of fluidity, while the cationic derivative TMA-DPH resides in the plasma membrane of the whole cells for a sufficient time for anisotropy measurements. Moreover, it has to be considered that plasma membrane is more ordered than intracellular membranes. The kinetics of incorporation of TMA-DPH was similar in keratinocytes isolated using trypsin-EDTA and those isolated using; dispase, however, the fluorescence anisotropy values were lower in keratinocytes isolated with dispase (0.260 +/- 0.01 vs 0.270 +/- 0.01, p = 0.029). This difference is probably related to modifications of lipid-protein interactions after trypsin treatment. Since no damage to plasma membrane after incubation with dispase seems to have been reported, we decided to use this separation procedure to study plasma membrane fluidity in psoriasis, a human pathological condition characterized by excessive cell proliferation and incomplete differentiation. Lower anisotropy values (0.260 +/- 0.01 vs 0.270 +/- 0.01, p = 0.001), indicating an increase in fluidity, were observed in keratinocytes isolated from skin of psoriatic patients than in epidermal cells isolated from normal human skin. We suggest that the measurement of fluorescence anisotropy in living cells is a convenient and useful tool to study membrane fluidity in human keratinocytes isolated from normal and diseased skin. Its application represents a technical advance because plasma membrane fluidity can be measured using very limited amounts of tissue, as obtained from biopsies.

Diphenylhexatriene↗
PubMed1996

Prognostic significance of cytoplasmic p53 overexpression in colorectal cancer. An immunohistochemical analysis.

p53 overexpression was studied by immunohistochemistry in 96 consecutive colorectal cancer patients, subdividing positive specimens according to two staining patterns: cytoplasmic or nuclear. Forty-seven per cent of the cases were p53 positive, a significant correlation being found with Dukes' stage (P = 0.0036). A prevalence of nuclear staining was observed in Dukes' B and cytoplasmic in Dukes' D stages. After 36 months, 23% of the patients had a recurrence, and 45% were p53 positive, all Dukes' C-D stage with cytoplasmic staining. The Kaplan-Meier curve showed a significant correlation between p53 cytoplasmic staining and disease-free survival period (P = 0.002). With respect to disease-free survival, the Cox proportional hazard regression test, comparing p53 positivity with Dukes' stage, showed the latter to be the most significant variable. In our series of patients, advanced Dukes' stage tumours were localised in the right colon, where a higher percentage of p53 positivity (67% versus 40% of the left side), as well as a higher frequency of cytoplasmic staining was observed. In conclusion, from the data obtained, a strong correlation between p53 cytoplasmic staining and patient prognosis is clearly indicated.

Adult↗
PubMed1996

Muscle tissue adaptations of high-altitude natives to training in chronic hypoxia or acute normoxia.

Twenty healthy high-altitude natives, residents of La Paz, Bolivia (3,600 m), participated in 6 wk of endurance exercise training on bicycle ergometers, 5 times/wk, 30 min/session, as previously described in normoxia-trained sea-level natives (H. Hoppeler, H. Howald, K. E. Conley, S. L. Lindstedt, H. Claassen, P. Vock, and E. R. Weibel. J. Appl. Physiol. 59: 320-327, 1985). A first group of 10 subjects was trained in chronic hypoxia (HT; barometric pressure = 500 mmHg; inspired O2 fraction = 0.209); a second group of 10 subjects was trained in acute normoxia (NT; barometric pressure = 500 mmHg; inspired O2 fraction = 0.314). The workloads were adjusted to approximately 70% of peak O2 consumption (VO2peak) measured either in hypoxia for the HT group or in normoxia for the NT group. VO2peak determination and biopsies of the vastus lateralis muscle were taken before and after the training program. VO2peak in the HT group was increased (14%) in a way similar to that in NT sea-level natives with the same protocol. Moreover, VO2peak in the NT group was not further increased by additional O2 delivery during the training session. HT or NT induced similar increases in muscle capillary-to-fiber ratio (26%) and capillary density (19%) as well as in the volume density of total mitochondria and citrate synthase activity (45%). It is concluded that high-altitude natives have a reduced capillarity and muscle tissue oxidative capacity; however, their training response is similar to that of sea-level residents, independent of whether training is carried out in hypobaric hypoxia or hypobaric normoxia.

Acclimatization↗
PubMed1996

Lactate and epinephrine during exercise in altitude natives.

We tested the hypothesis that the reported low blood lactate accumulation ([La]) during exercise in altitude-native humans is refractory to hypoxianormoxia transitions by investigating whether acute changes in inspired O2 fraction (FIo2) affect the [La] vs. power output (W) relationship or, alternatively, as reported for lowlanders, whether changes in [La] vs. W on changes in FIo2 are related to changes in blood epinephrine concentration ([Epi]). Altitude natives [n = 8, age 24 +/- 1 (SE) yr, body mass 62 +/- 3 kg, height 167 +/- 2 cm] in La Paz, Bolivia (3,600 m) performed incremental exercise with two legs and one leg in chronic hypoxia and acute normoxia (AN). Submaximal one- and two-leg O2 uptake (Vo2) vs. W relationships were not altered by FIo2. AN increased two-leg peak Vo2 by 10% and peak W by 7%. AN paradoxically decreased one-leg peak Vo2 by 7%, whereas peak W remained the same. The [La] vs. W relationships were similar to those reported in unacclimatized lowlanders. There was a shift to the right on AN, and maximum [La] was reduced by 7 and 8% for one- and two-leg exercises, respectively. [Epi] and [La] were tightly related (mean r = 0.81) independently of FIo2. Thus normoxia attenuated the increment in both [La] and [Epi] as a function of W, whereas the correlation between [La] and [Epi] was unaffected. These data suggest loose linkage of glycolysis to oxidative phosphorylation under influence from [Epi]. In conclusion, high-altitude natives appear to be not fundamentally different from lowlanders with regard to the effect of acute changes in FIo2 on [La] during exercise.

Adult↗
PubMed1996

Relationship between body mass index, age and upper airway measurements in snorers and sleep apnoea patients.

Anatomical pharyngeal and craniofacial abnormalities have been reported using upper airway imaging in snorers with or without obstructive sleep apnoea (OSA). However, the influences of the age and weight of the patient on these abnormalities remain to be established. The aim of this study was, therefore, to evaluate in a large population of snorers with or without OSA, the relationship between body mass index (BMI), age and upper airway morphology. One hundred and forty patients were referred for assessment of a possible sleep-related breathing disorder and had complete polysomnography, cephalometry and upper airway computed tomography. For the whole population, OSA patients had more upper airway abnormalities than snorers. When subdivided for BMI and age, however, only lean or younger OSA patients were significantly different from snorers as regards their upper airway anatomy. The shape of the oropharynx and hypopharynx changed significantly with BMI both in OSA patients and snorers, being more spherical in the highest BMI group due mainly to a decrease in the transverse axis. On the other hand, older patients (> 63 yrs), whether snorers or apnoeics, had larger upper airways at all pharyngeal levels than the youngest group of patients (< 52 yrs). For the total group of patients, upper airway variables explained 26% of the variance in apnoea/hypopnoea index (AHI), whereas in lean (BMI < 27 kg.m-2) or youngest (age < 52 yrs) subjects upper airway variables explained, respectively 69 and 55% of the variance in AHI. In conclusion, in lean or young subjects, upper airway abnormalities explain a major part of the variance in apnoea/hypopnoea index and are likely to play an important physiopathogenic role. This study also suggests that the shape of the pharyngeal lumen in awake subjects is more dependent on body mass index than on the presence of obstructive sleep apnoea. Further investigation looking at upper airway imaging for surgical selection in obstructive sleep apnoea should focus on lean and young patients.

Age Factors↗
PubMed1996

[Localised primary lesion of the right pulmonary artery in Takayasu's disease].

Takayasu's disease involves the pulmonary vessels in over 50% of cases. However, primary lesions of the pulmonary arteries are very rare. The authors report the cases of a 34 year-old Caucasian woman presenting with clinical and radiological signs of acute pulmonary embolism, but in whom the pulmonary angiography showed stenotic and occlusive lesions of the right pulmonary artery. MRI provided an accurate diagnosis by showing typical thickening of the pulmonary arterial walls.

Acute Disease↗
PubMed1995

The role of pulmonary CO2 flow in the control of the phase I ventilatory response to exercise in humans.

To gain an insight into the origin of the phase I ventilatory response to exercise (ph I) in humans, pulmonary ventilation (VE) and end-tidal partial pressures of oxygen and carbon dioxide (PETO2 and PETCO2, respectively) were measured breath-by-breath in six male subjects during constant-intensity exercise on the cycle ergometer at 50, 100 and 150 W, with eupnoeic normocapnia (N) or hyperpnoeic hypocapnia (H) established prior to the exercise test. Cardiac output (Qc) was also determined beat-by-beat by impedance cardiography on eight subjects during moderate exercise (50 W), and the CO2 flow to the lungs (Qc.Cv-CO2 where Cv-CO2 is concentration of CO2 in mixed veneous blood) was estimated with a time resolution of one breathing cycle. In N, the initial abrupt increase of VE during ph I (delta VE approximately 18 1.min-1 above rest) was followed by a transient fall. When PETCO2 started to increase (and PETO2 decreased) VE increased again (phase II ventilatory response, ph II). In H, during ph I delta VE was similar to that of N. By contrast, during ph II delta VE kept gradually decreasing and started to increase only when PETCO2 had returned to approximately 40 mmHg (5.3 kPa). Thus, as a result of the prevailing initial conditions (N or H) a temporal shift of the time-course of VE during ph II became apparent. No correlation was found between CO2 flow to the lungs and VE during ph I. These results are interpreted as suggesting that an increased CO2 flow to the lungs does not constitute an important factor for the initial hyperventilatory response to exercise. They are rather compatible with a neural origin of ph I, and would support the "neurohumoral" theory of ventilatory control during exercise.

Adult↗
PubMed1995

Mild iodine deficiency during fetal/neonatal life and neuropsychological impairment in Tuscany.

The neuropsychological performance of schoolchildren living in areas with present and past iodine deficiency in Tuscany was investigated. Children were submitted to: a) block design subtest of the Wechsler Intelligence Scale for Children-Revised (WISC-R) and a modified version of the WISC-R coding subtest which evaluate the general neuropsychological and cognitive performance, independently from familial cultural background; b) simple reaction time (RT) session which evaluates the efficiency of the whole information processing and nervous transmission mechanisms. Neuropsychological performance was tested in 107 children living in Borgo a Mozzano, an area of mild iodine deficiency (IDA) with a median urinary iodine excretion (UIE) of 64 micrograms/L (mean +/- SD: 80.1 +/- 57). One hundred and six sex and age-matched children living in Marina di Pisa, an iodine sufficient coastal village of Tuscany (ISA) with a median UIE of 142 micrograms/L (mean +/- SD: 173 +/- 95) were used as controls. Tests for neuropsychological performance were performed in 57 children living in the village of Vagli, an area with past iodine deficiency (PIDA): 30 children born before iodine prophylaxis (Group 1), when the median UIE was 32 micrograms/L (mean +/- SD: 47 +/- 22), 27 children born after the institution of iodine prophylaxis (Group 2), when the median UIE was 109 micrograms/L (mean +/- SD: 130 +/- 73). Sex and age-matched ISA-children were used as controls for each group. RTs were significantly delayed (p < 0.05) in IDA than in ISA children, while block design and coding subtests showed no significant difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1995

Factors limiting maximal O2 consumption: effects of acute changes in ventilation.

The response of the O2 transport system to acute changes in alveolar ventilation (VA) was analysed. The fractional limitations to maximal O2 consumption (VO2max) imposed by the lungs (ventilation, FV, and lung-blood transfer, FL), the cardiovascular system (FQ), and peripheral O2 diffusion (Fp) were calculated according to a multifactorial model. A reference set of data, describing the status of O2 transport at maximal exercise in normoxia was used. The effects of VA on VO2max were assessed on the assumption of a constant reference O2 flow in mixed venous blood (QVO2). The changes in reference data after given independent changes in VA were calculated by an iterative procedure, until the VO2max value compatible with the constant reference QVO2 was found, at PIO2 values of 150 (normoxia), 130, 110 and 90 Torr. The VO2max changes in normoxia were less than expected assuming a linear O2 transport system, because of the flatness of the O2 dissociation curve around normoxic PO2. This affected the cardiovascular resistance to O2 flow, and its changes counterbalanced the effects on VO2max of induced changes in VA. This phenomenon was reversed in hypoxia, as the steep part of the O2 dissociation curve was approached. The fractional limitations to VO2max in normoxia resulted as follows: FV and FL provided between 5 and 12%, FQ between 59 and 78%, and Fp between 13 and 19% of the overall VO2max limitation. In hypoxia, FV and FL increased and FQ decreased. At PIO2 = 90 Torr, when VA was halved, FV, FL, FQ and Fp amounted to 0.35, 0.31, 0.20 and 0.14, respectively.

Animals↗
PubMed1995

Kinetics of oxygen consumption during maximal exercise at different muscle temperatures.

The aim of this study was to test at maximal exercise the hypothesis of the temperature-dependence of the kinetics of O2 consumption (VO2), which predicts a greater O2 deficit as muscle temperature is decreased. Six male subjects underwent 3 min exercise bouts at the minimum power eliciting maximum O2 consumption (VO2max), at normal temperature (A) and after cooling the thigh muscles by water immersion (C). Breath-by-breath VO2 was measured together with muscle blood flow (Qm), blood lactate accumulation ("early lactate", eLa), heart rate and muscle temperature (Tm). The O2 deficit was calculated by standard procedure. Net VO2max was 2.92 +/- 0.85 (SD) and 3.19 +/- 0.71 l center dot min-1 in C and A respectively (P < 0.05). Correspondingly, maximum power was 20 W lower in C than in A. At exercise start, Tm was 35.0 +/- 1.2 and 27.5 +/- 1.8 degrees C in A and C respectively. O2 deficit was 2.25 +/- 0.53 and 3.05 +/- 1.12 l in A and C respectively. The corresponding eLa was 7.7 +/- 2.5 and 13.8 +/- 2.5 mM, (P < 0.05) while Qm was 376 +/- 92 and 290 +/- 50 ml center dot kg-1 center dot min-1 (P < 0.05) in A and C, respectively. The eLa increase in C is associated with an impaired muscle blood flow and decreased muscle O2 unloading, and does not completely explain the greater O2 deficit in C. The unexplained fraction of the latter is perhaps accounted for by a greater net alactic O2 deficit, in agreement with a temperature-dependent decrease of the velocity constants of oxidative reactions, as suggested by the tested hypothesis.

Adult↗
PubMed1995

Physico-chemical properties of membranes of recovered erythrocytes in blood autologous transfusion: a study using fluorescence technique.

Using fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its derivative trimethylammonium-1,6-diphenyl-1,3,5-hexatriene (TMA-DPH), we have investigated the fluidity in erythrocyte membranes isolated from intraoperatively and postoperatively recovered erythrocytes, compared to membranes isolated from untreated erythrocytes or stored red blood cells (RBCs). Fluorescence polarization (Pf) of DPH and TMA-DPH was not significantly modified in membranes isolated from intraoperatively and postoperatively recovered RBCs compared to membranes isolated from untreated fresh RBCs or stored RBCs. However, using 2-dimethyl-amino-6-lauroyl-naphtalene (Laurdan), a very sensitive molecule, a significant increase in polarity in membranes from stored RBCs compared to untreated, intraoperatively and postoperatively recovered RBCs was observed. Moreover, there was significantly higher susceptibility to oxidative stress in membranes isolated from stored RBCs, compared to untreated and intraoperatively or postoperatively recovered RBC membranes, both at baseline and after oxidative stress. Our results suggest that intraoperative and postoperative recovered RBCs are less damaged than stored RBCs.

Aged↗