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Biomedical subjects

G Ferretti

Publications and source records attributed to G Ferretti.

At least 127 records · Page 7Linked to original sources
PubMed1998

Registration of real and CT-derived virtual bronchoscopic images to assist transbronchial biopsy.

This paper describes research work motivated by an innovative medical application: computer-assisted transbronchial biopsy. This project involves the registration, with no external localization device, of a preoperative three-dimensional (3-D) computed tomography (CT) scan of the thoracic cavity (showing a tumor that requires a needle biopsy), and an intraoperative endoscopic two-dimensional (2-D) image sequence, in order to provide assistance in transbronchial puncture of the tumor. Because of the specific difficulties resulting from the data being processed, a multilevel strategy was introduced. For each analysis level, the relevant information to process and the corresponding algorithms were defined. This multilevel strategy, thus, provides the best possible accuracy. Original image processing methods were elaborated, dealing with segmentation, registration and 3-D reconstruction of the bronchoscopic images. In particular, these methods involve adapted mathematical morphology tools, a "daemon-based" registration algorithm, and a model-based shape-from-shading algorithm. This pilot study presents the application of these algorithms to recorded bronchoscopic video sequences for five patients. The preliminary results presented here demonstrate that it is possible to precisely localize the endoscopic camera within the CT data coordinate system. The computer can thus synthesize in near real-time the CT-derived virtual view that corresponds to the actual endoscopic view.

Biopsy, Needle↗
PubMed1998

Appraising pulmonary edema using supine chest roentgenograms in ventilated patients.

The role of portable, anteroposterior, supine chest X-rays (CXRs) in distinguishing hydrostatic pulmonary edema (HPE) from permeability pulmonary edema (PPE) in mechanically ventilated patients is controversial. We prospectively obtained and evaluated such CXRs in 33 supine, mechanically ventilated intensive-care-unit patients with pulmonary artery catheters. Three chest radiologists independently reviewed CXRs without clinical information and recorded the cardiothoracic (CT) ratio, vascular pedicle width (VPW), and other radiographic features commonly used to evaluate pulmonary edema. Hydrostatic pulmonary edema was associated with a larger CT ratio (p < 0.001), subjective impressions of cardiomegaly (p < 0.01), and increased VPW (p = 0.02). There was a significant correlation between the pulmonary artery occlusion pressure and the VPW (r = 0.45, p = 0.0076) and CT ratio (r = 0.52, p = 0.0016), as well as between the VPW and CT ratio (r = 0.49, p = 0.0032). Despite this detailed evaluation of the CXRs, the mean accuracy of the radiologists' clinical diagnosis of HPE versus PPE was 41%, and 15 of 19 (79%) of PPE patients showed one or more roentgenographic signs of volume overload. Receiver-operating-characteristic curves were constructed to determine optimum cut-off values of VPW and CT ratio associated with HPE. Hydrostatic pulmonary edema was found to correlate best using a VPW > 63 mm coupled to a CT ratio > 0.52 (p = 0.027). With this combination of objective criteria, radiologists' diagnostic accuracy could have been increased to 73%. We therefore conclude that measurements of CT ratio and VPW correlate with pulmonary artery occlusion pressure in supine, mechanically ventilated patients. Distinction of hydrostatic from permeability pulmonary edema is difficult using portable, supine CXRs, but readily assessed radiologic signs may contribute to the correct diagnosis.

Adult↗
PubMed1998

Successful meropenem therapy of a brain abscess and meningitis arising from acute purulent otomastoiditis: case report.

We describe a case of a 25-year-old female with an acute left otomastoiditis, accompanied by a left temporal extradural abscess with moderate perifocal edema and meningitis. Intravenous meropenem (2 g 8-hourly) and intravenous methylprednisolone (40 mg once daily) were commenced empirically. Teicoplanin (400 mg once daily intravenously) was added after 5 days when culture results were available. Teicoplanin was discontinued on day 25 but meropenem and methylprednisolone were continued for a further 15 days, after which the abscess completely resolved without sequelae. No treatment-induced adverse effects or seizures were observed. Thus, in selected patients, antibacterials (in conjunction with a corticosteroid) may be successfully used without surgery to treat brain abscesses and in such circumstances meropenem is a useful option for empiric therapy.

Adult↗
PubMed1998

Upper airway changes in snorers and mild sleep apnea sufferers after uvulopalatopharyngoplasty (UPPP).

OBJECTIVES: We used upper airway (UA) imaging in 20 patients to determine (1) whether an effective enlargement of the UA is obtained after uvulopalatopharyngoplasty (UPPP), and (2) whether UA modifications explain the results of such surgery. METHODS: Cephalometric measurements were made to assess the posterior airway space, the length and width of the soft palate, and the distance between the hyoid bone and the mandibular plane. Pharyngeal CT measured the airway cross-sectional area (CSA) at each 10-mm slice from 10 mm above (-10) to 40 mm below (+40) the hard palate. Polysomnography was performed before and after surgery (10+/-10 [SD] months). Good responders were defined by an apnea-hypopnea index (AHI) of <10 postsurgery or, in patients in whom AHI was initially <10, a reduction of AHI >50% of the initial AHI. RESULTS: Twenty patients (age=45+/-11 years) were studied. For the whole group, the mean body mass index (26+/-4 kg/m2) and AHI (14+/-13 vs 18+/-16/h) were unchanged after UPPP. The results of the surgery were mediocre with 7 good responders (35%) and 13 nonresponders (65%) defined by polysomnographic criteria. The only changes on UA imaging for the group as a whole after UPPP were decrease in length (40+/-6 vs 29+/-5 mm, p< or =0.0006) and increase in width of the soft palate (11.5+/-2.7 vs 13.6+/-3.5 mm, p< or =0.006). The increase or decrease in minimal CSA at the oropharyngeal (OP) level after UPPP was significantly correlated with the change in AHI (r=-0.54, p<0.02). Moreover, the changes in CSA obtained at the OP level were significant only in the patients who responded favorably to UPPP (7 vs 13 nonresponders). CONCLUSIONS: Postoperative OP enlargement is associated with a good outcome of UPPP. Persistent narrowing in nonresponders could be due to the increase in soft palate width after surgery.

Adult↗
PubMed1998

[Puerperal thrombophlebitis and the ovarian vein with extension to the inferior vena cava].

PURPOSE: To assess US, CT and MR findings in women having puerperal ovarian vein thrombosis with clot protrusion into the inferior vena cava. PATIENTS, MATERIAL AND METHODS: We retrospectively reviewed the duplex US (n = 9), CT (n = 5) and MR (n = 5) examinations of 9 patients with 8 right ovarian vein thrombosis, and one left ovarian vein thrombosis. RESULTS: US findings allowed for the diagnosis of ovarian vein thrombosis in all patients in showing enlarged tubular echogenic thrombus within the retroperitoneum with clot protrusion in the IVC in all cases. CT scan and MRI demonstrated ovarian vein thrombosis in all the cases in which it was performed but failed to show a mobile thrombus within the IVC in one patient. CONCLUSION: Duplex US is a reliable technique to show puerperal ovarian vein thrombosis and its extension to the IVC. CT scan and MR imaging can be used to precise the extension to the IVC.

Adult↗
PubMed1998

[Does a universal strategy of acute pulmonary embolism diagnosis exist today?].

In this review, we demonstrate that there is no universal diagnostic strategy for non-severe acute pulmonary embolism. The first part of the article is devoted to the concept of thromboembolic disease: its frequency, severity and diagnostic difficulties. The second part analyzes the tools used for diagnosis of pulmonary angiography, noninvasive venous studies, and helical CT angiography. The last part discusses current diagnostic algorithms for pulmonary embolism and the changes that may be introduced by the use of helical CT in clinical practice. The potential for MR imaging id discussed.

Acute Disease↗
PubMed1998

Fibromyxoma of the retropharyngeal space: MR appearance with pathologic correlation.

A 19-year-old woman reported difficulties in swallowing and breathing. A submucosal mass, shown by MR imaging in the retropharyngeal space, was the cause of her symptoms. Histologically, the mass proved to be a fibromyxoma. The oval well-delineated lesion appeared hypointense relative to muscle and strongly enhanced after injection of contrast material on T1-weighted images; on T2-weighted images, it appeared hyperintense, and was seen to contain fibrous septa, which were hypointense on all sequences. This case delineates the characteristic MR features of a fibrous component within a rare benign tumor of the retropharyngeal space.

Adult↗
PubMed1997

The effects of breathing He-O2 mixtures on maximal oxygen consumption in normoxic and hypoxic men.

1. The hypothesis that the ventilatory resistance to O2 flow (RV) does limit maximal O2 consumption (VO2,max) in hypoxia, but not in normoxia, at least in non-athletic subjects, was tested. RV was reduced by using He-O2 mixtures. 2. VO2,max was measured during graded cyclo-ergometric exercise in eight men (aged 30 +/- 3 years) who breathed N2-O2 and He-O2 mixtures in normoxia (inspired oxygen fraction (FI,O2) = 0.21) and hypoxia (FI,O2 = 0.11). O2 consumption, expired and alveolar ventilations (VE and VA, respectively), blood lactate and haemoglobin concentrations, heart rate and arterial oxygen saturation (Sa,O2) were determined at the steady state of each work load. Arterial O2 and CO2 partial pressures (Pa,O2 and Pa,CO2, respectively) were measured at rest and at the end of the highest work load. 3. Maximal VE and VA were significantly increased by He-O2 breathing in normoxia (+27 and +18%, respectively), without significant changes in Pa,O2, Sa,O2 and VO2,max. In hypoxia, VE and VA increased (+31 and +24%, respectively), together with Pa,O2 (+17%), Sa,O2 (+6%) and VO2,max (+14%). 4. The results support the hypothesis that the role of RV in limiting VO2,max is negligible in normoxia. In hypoxia, the finding that higher VE and VA values during He-O2 breathing led to higher VO2,max values suggests a greater role of RV as a limiting factor. It is unclear whether the finding that the VO2,max values were the same during He-O2 and N2-O2 breathing in normoxia is due to a non-linear response of the O2 transfer system, as previously proposed.

Adult↗
PubMed1997

The interplay of central and peripheral factors in limiting maximal O2 consumption in man after prolonged bed rest.

1. The effects of bed rest on the cardiovascular and muscular parameters which affect maximal O2 consumption (VO2,max) were studied. The fractional limitation of VO2,max imposed by these parameters after bed rest was analysed. 2. The VO2,max, by standard procedure, and the maximal cardiac output (Qmax), by the pulse contour method, were measured during graded cyclo-ergometric exercise on seven subjects before and after a 42-day head-down tilt bed rest. Blood haemoglobin concentration ([Hb]) and arterialized blood gas analysis were determined at the highest work load. 3. Muscle fibre types, oxidative enzyme activities, and capillary and mitochondrial densities were measured on biopsy samples from the vastus lateralis muscle before and at the end of bed rest. The measure of muscle cross-sectional area (CSA) by NMR imaging at the level of biopsy site allowed computation of muscle oxidative capacity and capillary length. 4. The VO2,max was reduced after bed rest (-16.6%). The concomitant decreases in Qmax (-30.8%), essentially due to a change in stroke volume, and in [Hb] led to a huge decrease in O2 delivery (-39.7%). 5. Fibre type distribution was unaffected by bed rest. The decrease in fibre area corresponded to the significant reduction in muscle CSA (-17%). The volume density of mitochondria was reduced after bed rest (-16.6%), as were the oxidative enzyme activities (-11%). The total mitochondrial volume was reduced by 28.5%. Capillary density was unchanged. Total capillary length was 22.2% lower after bed rest, due to muscle atrophy. 6. The interaction between these muscular and cardiovascular changes led to a smaller reduction in VO2,max than in cardiovascular O2 transport. Yet the latter appears to play the greatest role in limiting VO2,max after bed rest (> 70% of overall limitation), the remaining fraction being shared between peripheral O2 diffusion and utilization.

Adult↗
PubMed1997

Reduced beta-strand content in apoprotein B-100 in smaller and denser low-density lipoprotein subclasses as probed by Fourier-transform infrared spectroscopy.

The secondary structure of apolipoprotein B-100 in low-density lipoprotein (LDL) subfractions was analysed by Fourier-transform IR spectroscopy. LDLs were isolated in three density ranges by gradient centrifugation of human plasma from healthy volunteers. The spectra revealed differences in the lipid content and composition of the three LDL fractions. The secondary structure of apolipoprotein B-100 was the same in the two fractions corresponding to the large less-dense LDL particles, whereas a lower content of beta-strands was found in the third fraction corresponding to the smaller denser LDL particles. Analysis of the spectroscopic data suggests that, in the same set of LDL subfractions, the particle size is probably the cause of the observed differences in apolipoprotein B-100 secondary structure.

Apolipoprotein B-100↗
PubMed1997

The decrease of maximal oxygen consumption during hypoxia in man: a mirror image of the oxygen equilibrium curve.

1. Endurance athletes (E) undergo a marked reduction of arterial O2 saturation (Sa,O2) at maximal exercise in normoxia, which disappears when they breathe hyperoxic mixtures. In addition, at a given level of hypoxia, the drop in maximal O2 consumption (VO2,max) is positively related to the individual normoxic VO2,max. 2. These data suggest that the curve relating VO2,max to PI,O2 may be steeper and perhaps less curved in E than in sedentary subjects (S) with low VO2,max values because of the greater hypoxaemia in the latter, whence the hypotheses that (i) the relationship between VO2,max and PI,O2 may be set by the shape of the oxygen equilibrium curve; and (ii) the differences between E and S may be due to the different position on the oxygen equilibrium curve on which these subjects operate. These hypotheses have been tested by performing a systematic comparison of the VO2,max or Sa,O2 vs. PI,O2 relationships in E and S. 3. On ten subjects (five S and five E), VO2,max was measured by standard procedure during cycloergometric exercise. Sa,O2 was measured by finger-tip infrared oximetry. Arterialized blood PO2 (Pa,O2) and PCO2 (Pa,CO2) were determined in 80 microliters blood samples from an ear lobe. The subjects breathed ambient air or a N2-O2 mixture with an inspired O2 fraction (FI,O2) of 0.30, 0.18, 0.16, 0.13 and 0.11, respectively, VO2,max was normalized with respect to that obtained at the highest FI,O2. 4. The relationships between Sa,O2 or normalized VO2,max and FI,O2 (or PI,O2) had similar shapes, the data for E being systematically below and significantly different from those for S. Linear relationships between Sa,O2 and normalized VO2,max, statistically equal between E and S, were found. 5. We conclude that the relationships between either VO2,max or Sa,O2 and FI,O2 (or Pa,O2) may indeed be the mirror images of one another, implying a strict link between the decrease of VO2,max in hypoxia and the shape of the oxygen equilibrium curve, as hypothesized.

Adult↗
PubMed1997

Cytotoxicity of bile salts against biliary epithelium: a study in isolated bile ductule fragments and isolated perfused rat liver.

We evaluated cytotoxic effects of different unconjugated and glycine- and taurine-conjugated bile salts (BS) against bile duct epithelial cells in isolated bile ductule fragments and isolated perfused rat liver. Ultrastructural morphometric studies were performed in polarized rat bile ductule fragments exposed in vitro to increasing concentrations (10-100 micromol/L) of lithocholate (LCA), deoxycholate (DCA), chenodeoxycholate (CDCA), cholate (CA), ursodeoxycholate (UDCA), their taurine-conjugates, and glycoconjugates of cholic (GCA) or chenodeoxycholic acid (GCDCA) for 20, 30, or 75 minutes. To evaluate the cytotoxicity of unconjugated hydrophobic bile salts against biliary epithelium (BDE) in the whole liver, livers were isolated from rats with impaired taurine-conjugation capacity (beta-alanine treatment) and perfused for 70 minutes with 2 micromol/min LCA (n = 6), CDCA (n = 6), CA (n = 6), or 0.5 micromol/min tauro-LCA (n = 4). In isolated bile ductule fragments, hydrophobic unconjugated bile salts (LCA, CDCA, DCA) induced a marked damage of intracellular organelles, mainly mitochondria. The damage started at a concentration of 10 micromol/L and became prominent at concentrations higher than 50 micromol/L. No damage of the apical and basolateral membrane was seen and tight junctions appeared intact. UDCA, taurine and glycoconjugated bile salts failed to induce any evident ultrastructural alteration. In taurine-depleted isolated livers, perfused with LCA, CDCA, or CA, bile duct epithelial cells showed no evidence of intracellular damage, despite the increased biliary excretion of unconjugated BS. Marked alterations of the apical cell membrane were seen only in livers perfused with LCA and in isolated segments of the biliary epithelium. In contrast with biliary epithelium, hepatocytes showed prominent subcellular damage with CA and CDCA, and profound alterations of the canalicular membrane with LCA and tauro-LCA. We have shown that, in vitro, BDE cells are not damaged by taurine- or glycine-conjugated BS, but they are very sensitive to cytotoxicity of hydrophobic unconjugated BS. Such sensitivity is not present in the whole liver, probably because of the specificity of BS transport processes, the microvascular architecture of the bile ductal system, and the presence in bile of a physiological surfactant, such as phospholipids.

Animals↗
PubMed1997

Effects of endurance training on oxidative capacity and structural composition of human arm and leg muscles.

Six healthy subjects performed endurance training of the same duration with legs and arms consecutively. Performance and muscle structure were measured before and after training in lower and upper limbs. Training induced similar increases in maximal oxygen consumption (6 +/- 1 vs. 7 +/- 2 mL min-1 kg-1: legs vs. arms, P > 0.05) and mitochondrial volume in leg and arm muscles (42 +/- 12 vs. 31 +/- 11%: legs vs. arms, P > 0.05). The gain in mitochondrial volume after training was achieved solely by increasing the fraction of mitochondria (+40 +/- 11%, P < 0.05) in the same muscle volume (+2 +/- 2%, P > 0.05) in the legs. In contrast, increased muscle volume (+14 +/- 3%, P < 0.05), in addition to a tendency for an increase in mitochondrial fraction (+16 +/- 11%, P > 0.05), occurred in the arms after training. Thus, similar improvements in muscle oxidative capacity in upper and lower limbs were brought about by different mechanisms. It is suggested that due to infrequent use and a lack of load-bearing function, arm muscle volume is underdeveloped in untrained, sedentary or detrained/injured subjects and that the mode of endurance training used in this study is sufficient to enlarge arm muscle volume as well as aerobic capacity.

Adult↗
PubMed1997

Multifocal alveolar hyperplasia associated with lymphangioleiomyomatosis in tuberous sclerosis.

Multifocal alveolar hyperplasia associated with pulmonary lymphangioleiomyomatosis is reported in a 21-year-old woman with tuberous sclerosis. Beside the cystic lesions of lymphangioleiomyomatosis, the tomography showed nodules up to 8 mm in both upper lobes. A proliferation of type II pneumonocytes and Clara cells lining the alveolar walls in an adenoma-like pattern was observed. Nuclear atypia, mitoses and necrosis were not observed, providing evidence against multicentric bronchioloalveolar carcinoma or micronodular atypical alveolar adenomatous hyperplasia. Whereas the lymphangioleiomyomatosis lesions showed strong positivity for HMB45 and expressed oestrogen and progesterone receptors, the alveolar hyperplasia was negative for these markers as it was for carcinoembryonic antigen, p53 and MIB1 antibodies. Multifocal alveolar hyperplasia in tuberous sclerosis is probably a benign hamartomatous lesion in our case without progression on a 2-year follow-up. Its histogenesis is unknown, but is possibly related to chromosome instability.

Adult↗
PubMed1997

Cardiovascular changes during deep breath-hold dives in a pressure chamber.

Electrocardiogram, cardiac output, and blood lactate accumulation were recorded in three elite breath-hold divers diving to 40-55 m in a pressure chamber in thermoneutral (35 degrees C) or cool (25 degrees C) water. In two of the divers, invasive recordings of arterial blood pressure were also obtained during dives to 50 m in cool water. Bradycardia during the dives was more pronounced and developed more rapidly in the cool water, with heart rates dropping to 20-30 beats/min. Arrhythmias occurred, particularly during the dives in cool water, when they were often more frequent than sinus beats. Because of bradycardia, cardiac output decreased during the dives, especially in cool water (to <3 l/min in 2 of the divers). Arterial blood pressure increased dramatically, reaching values as high as 280/200 and 290/150 mmHg in the two divers, respectively. This hypertension was secondary to peripheral vasoconstriction, which also led to anaerobic metabolism, reflected in increased blood lactate concentration. The diving response of these divers resembles the one described for diving animals, although the presence of arrhythmias and large increases in blood pressure indicate a less perfect adaptation in humans.

Adult↗