Biomedical subjects

C Marchetti

Publications and source records attributed to C Marchetti.

At least 73 records · Page 4Linked to original sources

PubMed1996

Structure of the lymphatic microcirculation in the human urinary bladder with different intraluminal pressure and distension.

The localization, morphology and fine structure of initial lymphatic vessels in the mucosa of the empty and distended urinary bladder were studied. Endoscopic transurethral biopsies of the empty (collapsed) bladder showed under light and electron microscopy numerous intramural lymphatics with a dilated lumen and thin profile. Contacts between endothelial cells were single, overlapping, interlocking, and open while the perivascular connective tissue was filled by fascicles of collagen fibers. In the most superficial layer (subepithelial mucosa), lymphatics were not seen. Biopsies obtained under elevated intraluminal pressure and distension showed on light and electron microscopy lymphatic vessels with small lumens characteristically reduced to irregular slits. Endothelial cell contacts were simple or overlapping; open junctions were rare. The perivascular connective tissue was dense and collagen and elastic fibers often abutted one another. These findings support that with a distended or expanded urinary bladder, the effect of increased intraluminal pressure on the superficial (mucosal) layer radially pulls on the connective tissue that in turn compresses the initial lymphatics thereby restricting lymph transport.

Adult↗

PubMed1996

Structure of the initial lymphatics of the human urinary bladder with invasive urothelial tumors.

The ability of urothelial tumors of the urinary bladder to metastasize via the lymphatic circulation and the extent of metastatic involvement of regional lymph nodes is an important parameter in the staging and prognosis of these neoplasms. Accordingly, we examined the site and morphology of initial lymphatic vessels in the mucosa of the human urinary bladder in patients with invasive transitional cell carcinoma. Lymphatics in the papillary tumoral mass was also examined. Endoscopic transurethral biopsies from the urinary bladder of 120 patients with invasive transitional cell papillary carcinoma were utilized for this study. Biopsy from the uninvolved lateral wall of the same patient was utilized as a control. On histopathology of biopsies of neoplastic tissues, initial lymph vessels were seen in the deeper region of the mucosa but not in the subepithelial layer nor in the stroma of the tumoral papillae. The latter were often associated with arteriolar and venular vessels. When edema and inflammation occurred in peritumoral regions, lymphatics showed a dilated lumen, non-indented wall with dissociated perivascular collagen and elastic fibers. Tumoral permeation or embolization of lymphatics was seen in 12% of patients with invasive tumors, and these lymphatic vessels did not display significant morphologic changes. The absence of initial lymphatics in the stroma of tumoral papillae and in infiltrated subepithelial regions of the urinary bladder may explain the absence of lymph node metastasis in early-stage invasive urothelial tumors.

Adult↗

PubMed1996

Craniofacial fibrous dysplasia and Ollier's disease: combined transfrontal and transfacial resection using the nasal-cheek flap.

Fibrous dysplasia and Ollier's disease (skeletal chondromatosis) are bone lesions that result from disorders occurring during ossification. Here we report on a patient suffering from Ollier's disease in whom polyostotic fibrous dysplasia was detected. The main problem for this 20-year-old man was a nasoethmoidorbital cartilaginous mass causing nasal obstruction, nonreducible eye proptosis, and sleep apnea. The lesion was approached by means of a combined route, ie, transfrontally and transfacially (nasal-cheek flap). The possible pathogenetic links existing between the two lesions and the problems involved in surgical treatment are discussed.

Adult↗

PubMed1996

Weibel-Palade bodies and lymphatic endothelium: observations in the lymphatic vessels of normal and inflamed human dental pulps.

The Weibel-Palade bodies, cytoplasmic organelles characterizing endothelial cells, are abundant in lymphatic capillary endothelium of human dental pulp. Their number almost double in the lymphatic vessels of inflamed dental pulps. The data were discussed and compared with others concerning the demonstration of the presence of von Willebrand factor and P-selectin in the Weibel-Palade bodies of lymphatic vessels in mesentery. It is suggested that the increase in the number of Weibel-Palade bodies observed in dental pulp may be connected along with those in the lymphatic vessels to the function that these adhesive molecules play during inflammatory states.

Dental Pulp↗

PubMed1996

[Free-flap fibula for the reconstruction of composite mandibular defects].

The advent of microsurgery has revolutionized the reconstruction of composite tissue defects of the mandibular region. Well-vascularized bone and soft-tissues can be used to repair any kind of oromandibular defects and many of the morphological and functional goals of mandibular reconstruction can now be achieved. The ideal flap should provide a vascularized bone of sufficient length and height, easily shaped to match the original mandible with a thin, abundant soft-tissue component. The donor site morbidity should be minimal and a two-team approach possible. Different flaps have been used for mandibular reconstruction including fibula, iliac crest, radius and scapula. According to us, fibula free-flap satisfies many of these requirements and is the flap of choice in most cases of difficult mandibular reconstruction. 8 fibula free flaps were used in 6 cases of primary and 2 cases of secondary reconstructions. The defects were secondary to resections of oral cancers in 4 cases and of osteosarcomas in 4 cases. The mandibular defects were between 8 and 16 cm in length. Multiple osteotomies were used to shape the bone and miniplates were utilized for rigid fixation of the osteotomized bone and of the remaining mandible. An important soft-tissue defect was present in 6 cases requiring a skin paddle for oral lining. In 6 cases there was a complete survive of the flaps with very satisfactory results and good mandibular contour. There was one flap failure for a venous thrombosis and in one case the flap was removed after 8 days for complications independent of the microvascular technique. Donor site morbidity was minimal with no significant gait disturbance. In conclusion, the advantages of microvascular surgery and the reliability of fibula free-flap make it an attractive and versatile option in one-stage reconstruction of composite tissue defects in the mandibular region.

Adult↗

PubMed1996

The use of pulmonary allografts for aortic valve replacement. Short term results and comparative morphometric analysis of the aortic and pulmonary valves.

UNLABELLED: The satisfactory results of aortic valve replacement with pulmonary autograft and the limited availability of aortic allografts prompted us to use the pulmonary valve as an aortic valve substitute and to perform a morphometric analysis of the two valves in cadavers. CLINICAL STUDY: From March 1994 to March 1995 20 patients underwent an aortic valve replacement (AVR) with a pulmonary allograft (PA). Twelve patients were men, 8 women; age ranged from 15 to 58 years. In 4 cases the indication to AVR was an infective endocarditis which was acute in two patients. Functional class was NYHA II in 18 cases and NYHA III in 2 patients with active endocarditis. Left ventricular ejection fraction (LVEF%) was preserved in the majority of patients (mean LVEF=53% range 36% to 65%). End diastolic aortic valve diameters were measured by bidimensional echocardiography in parasternal long axis view and ranged from 18 mm to 29 mm. The diameters of the allografts implanted ranged from 19 mm to 27 mm. Donors age ranged from 19 years to 55 years. We tried to use the allograft from the youngest donor available. The surgical technique was the classic "Ross" coronary freehand implantation in 11 cases, a "Miniroot" implant in 8 instances and a "Miniroot" implant combined with a "Nicks" annular enlargment in 1 case. Aortic cross clamping ranged from 66 mm to 118 m (92m+/-10m). One patient died (5%) of infarction. In this patient the allograft was replaced with a mechanical valve because the echocardiography showed a rapidly increasing aortic regurgitation. At hospital discharge a slight aortic regurgitation was detected in 2 cases. In these two patients, whose annulus diameters were 26 mm and 28 mm respectively, we adopted a classic freehand technique of implantation. Mean postoperative transvalvular gradient was 4 mmHg+/-3 mmHg. The follow-up ranges from 45 days to 14 months (mean 8 months). The aortic regurgitation in the two cases remains stable and no new aortic regurgitations have been detected to date. No embolic or infective episodes occurred during the follow-up. ANATOMIC STUDY: Analysis was performed on 6 couples of valves obtained from cadevers without evidence of previous valvular disease. The normalized Free Edge (FE) dimensions and Leaflet Surfaces (LS) of the pulmonary valve (PV) proved to be larger than the corresponding aortic (AV) measurements (Free edge/Diameter: PV 1.25+/-0.2 vs AV 1.16+/-0.2 p<0.05; Annular Attachment/Diameter PV 1.9+/-0.1 vs AV 1.74+/-0.2 p=NS; Valve Surface/Leaflet Surface PV 0.97+/-0.2 vs AV 0.80+/-0.2 p=0.004) indicating that the PV has a larger coapting surface.

Adolescent↗

PubMed1995

Taxol cytotoxicity on human leukemia cell lines is a function of their susceptibility to programmed cell death.

Taxol is the prototype of a class of antineoplastic drugs that target microtubules. It enhances tubulin-monomer polymerization and stabilizes tubulin polymers, increasing the fraction of cells in the G2 or M phase of the cell cycle. We report that treatment of HL-60 and U937 myeloid cell lines with 1-10 microM taxol induces DNA fragmentation and the appearance of morphological features consistent with the process of apoptosis. Taxol-induced apoptosis is inhibited neither by cycloheximide nor by actinomycin D and therefore appears to be independent of new protein synthesis. Taxol causes arrest in the G2 phase of the cell cycle and affects cell viability but does not induce DNA fragmentation in the K562 erythromyeloid cell line. Protein-synthesis inhibitors, colcemid, ionomycin, and starvation, known to trigger apoptosis, proved ineffective as well. These results suggest that the antineoplastic effect of taxol is mediated in susceptible cell lines by induction of the apoptotic machinery and that K562 partial resistance may depend upon the intrinsic inability of these tumor cells to undergo apoptosis.

Apoptosis↗

PubMed1995

A microscopic and immunocytochemical study of structural changes in dysfunctional human temporomandibular joint discs.

The central part of 12 articular discs from patients with serious alterations in function of the temporomandibular joint were investigated. The control discs were removed at autopsy from individuals who did not have any such functional defects. The anomalous discs had an increased cellular component; fibrocytes, fibroblasts, numerous myofibroblasts and, less frequently, smooth muscle cells and mast cells were present. The myofibroblasts, which had numerous bundles of thin filaments in the cytoplasm, were positive to the immunocytochemical reaction with antibody to alpha-smooth muscle actin. In one disc only a large part had changed into a mostly fatty tissue. In the majority of the altered discs, the part examined, which usually is neither vascularized nor innervated, was characterized by the presence of numerous blood vessels. Besides the capillary network several larger vessels were present. In one disc, several myelinated and unmyelinated fibres, isolated or in nerve bundles, were also seen. These observations show that the disc fibrous tissue may undergo deep structural modifications that appear to indicate not only a capacity for repair but also an ability to adapt to new functional conditions.

Actin Cytoskeleton↗

PubMed1995

Functional characterization of the effect of nimodipine on the calcium current in rat cerebellar granule cells.

1. We investigated the effect of nimodipine on the calcium current in dissociated cerebellar granule cells from 8-day-old rats. We measured the whole cell current and the depolarization-induced internal calcium elevation in Fura2-loaded cells exposed to high-potassium solutions. 2. Nimodipine maximally depressed the peak calcium current from holding potential (Vh) = -80 mV by 25% and the inactivation resistant residual current from Vh = -50 mV by 44%. The nimodipine-sensitive current had the same amplitude under both conditions and the half-maximal inhibition concentration (IC50) was close to 50 nM. 3. In contrast to other components of the calcium current, the nimodipine-sensitive current did not inactivate significantly during 1-s depolarization and it was weakly sensitive to the holding potential and to depolarizing conditioning prepulses. The effect of nimodipine was higher on the current elicited by small depolarizations and the current at -30 mV was depressed by < or = 70%. Depolarizing prepulses enhanced the effect of 1 nM (but not that of 1 microM) nimodipine. 4. In Fura2-loaded cells, nimodipine strongly antagonized the internal calcium rise due to superfusion with 15-75 mM potassium. The effect was significantly more potent on the internal calcium rise determined by lower depolarizations, with 80% inhibition of the peak response to 25 mM KCl. The dose dependence of this depression was best approximated by a two-site curve with IC50(1) = 0.27 nM and IC50(2) = 65 nM. The time course of recovery was dependent on the duration of treatment, suggesting a close interaction between nimodipine and the lipid membrane. 5. The effect of 1 microM nimodipine was not influenced by predepolarizations determined by treatments with calcium-free elevated potassium solutions, but when doses as low as 1 nM were applied the fast decay of the calcium level suggested a voltage dependence of the effect. Nimodipine also depressed < or = 90% of the plateau phase of the depolarization-induced internal calcium rise at different depolarizations. 6. Incubation in omega-conotoxin, fraction GVIA (5 microM) did not cause any significant decrease in the calcium response, whereas omega-agatoxin, fraction IVA (0.5 microM) depressed the calcium peak by 40-60% and its effect was additive with that of nimodipine. 7. We conclude that the nimodipine-sensitive current is a persistent, inactivation-resistant current that activates at a membrane potential lower than the other components and is likely to be responsible for the elevation of calcium determined by nonovershooting, prolonged depolarizations in these cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1995

Endoarticular loose bodies and calcifications of the disk of the temporomandibular joint: morphological features and chemical composition.

We studied articular disks and endoarticular loose bodies taken from patients suffering from different types of temporomandibular joint (TMJ) pathology. The scanning electron microscopy (SEM) analysis of the disks and the endoarticular loose bodies was followed by a chemical-compositional analysis using an energy dispersive spectrometer (EDS) and by characterization of the crystalline phases by X-ray powder diffraction (XRD). The articular disks were composed of a central radiopaque area lacking any evident structural features, surrounded by compact bundles of collagen fibers. EDS and XRD analyses showed that endodiscal radio-opaque areas were hydroxyapatite. By SEM, we observed a fibrous network only in circumscribed areas of the endoarticular loose bodies. The chemical-compositional analysis showed that the loose bodies were composed of calcite (CaCO3). The results of this investigation, along with the clinical history of the patients, allow us to formulate some hypotheses regarding the etiopathogenesis of these structural anomalies. The endodiscal calcifications could be the result of a chronic inflammatory process that produces displastic alterations of the articular disk. Moreover, an acute inflammatory process with modifications in the mechanisms of the synovial fluid turnover seems to be the event that leads to the formation of endoarticular loose bodies.

Calcinosis↗

PubMed1995

Pharmacological types of calcium channels and their modulation by baclofen in cerebellar granules.

Voltage-dependent calcium currents were measured by whole-cell recording technique in cultured cerebellar granule neurons from 8 d old rats, in 10 mM BaCl2 and with a holding potential of -80 mV. A saturating dose (10 microM) of the dihydropyridine nimodipine reversibly inhibited the maximum current by 25% and the dose dependence showed IC50 close to 50 nM. omega-Conotoxin GVIA (cgtx, 5 microM) and omega-agatoxin IVA (agatx, 200 nM) irreversibly inhibited the current by 17% and by 47%, respectively. The effect of nimodipine was additive with that of the toxins. The GABAB agonist (+/-)baclofen, or (-)baclofen (100 microM), reduced the calcium current by 30 +/- 5%, with a IC50 4 microM. The effect was mediated by a pertussis toxin-sensitive G-protein. In cells treated with cgtx during the experiment or preincubated with the toxin for 30 min, the effect of baclofen was significantly reduced. However, the action of baclofen was not confined to cgtx-sensitive channels: application of nimodipine or agatx resulted in a 50% reduction of the baclofen effect as well. In contrast, baclofen inhibited approximately the same amount of current both before and after the increase caused by the dihydropyridine agonist BayK 8644 and did not modify the slow BayK-induced tail current. These results indicate (1) the modulation through GABAB receptors does not clearly discriminate between pharmacologically distinct calcium channels and (2) L-type calcium channels represent an heterogeneous population in these neurons.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1995

[Quality assurance in diagnostic radiology using an automated system. Experience and results].

The authors report their personal experience with the use of an integrated quality control system in the radiology department. The system we used was the RTI DIGI-X Plus, a Swedish-made product, allowing a wide range of parameters to be measured on diagnostic X-ray units for general radiography, mammography and fluoroscopy. Data can be retrieved with a minimum number of measurements. The "oRTIgo" software improves the quality assurance system and ensures document compliance with international recommendations. The equipment consists of a detector unit, a processor and a display unit. The detector consists of a rotating holder with 12 combinations of metal filters of various thickness mounted in front of two photo-diodes covered with identical X-ray intensifying gadoliniumoxysulfide screens. This unit is connected to a data acquisition system controlled by a microcomputer. Peak tube voltage and total tube filtration are derived from the ratio of detector signals. The relationship between this ratio and the measured quantity is determined by a calibration procedure. Furthermore, exposure time "mAs" value, "mAs" linearity and exposure (or kerma in air) can be measured. Digital storage can be performed and input signals displayed. A serial interface is used to communicate with a PC for QC management purposes. An error propagation model is used to determine the inaccuracy of peak tube voltage measurements. With the DIGI-X Plus system, measurements can be carried out in a shorter time and the stored data reprocessed later on. After QA testing on 20 X-ray units in the radiology department, in vivo doses were measured using a TLD Harshaw 100 on 46 randomly selected patients undergoing chest examinations. The results are reported and analyzed following the NRPB protocol and show high agreement with the recommended values.

Humans↗

PubMed1995

The lymphatic vessels and their relationship to lymph formation in the human urinary bladder.

After endoscopic transurethral biopsies of normal human urinary bladder, an extensive network of small initial lymphatic vessels was depicted by means of light and electron microscopy. Using light microscopy, lymphatic vessels were seen in the mucosa and submucosa and formed a complex network in the detrusor muscular coat. These lymphatics were characterized by an irregular and attenuated wall and increased in number and size from the superficial to the deeper region of the bladder. Ultrastructurally, the lymphatic wall was characterized by endothelial cells joined together end-to-end or by complicated interdigitations. Often intercellular channels and gaps between two contiguous endothelial cells were present. A broad network of elastic and collagen fibers joined the lymphatic endothelial wall to the neighboring connective tissue. Nevertheless, as far as the fibrillar component was concerned, the vesical intramuscular lymphatic endothelial wall lacked elastic fibers. These anatomic variations were examined in reference to lymph formation in an organ (the urinary bladder) which undergoes continual changes in volume and pressure.

Adult↗

PubMed1995

Ultrastructural Localization of elastin-like immunoreactivity in the extracellular matrix around human small lymphatic vessels.

The distribution of elastin-like immunoreactivity around small lymphatic vessels was investigated in three different human tissues (skin, heart and dental pulp) using high resolution immunocytochemistry. Quantitative assessment of the immunogold reaction was performed with an image analysis system. Intense and moderate elastin-immuno-reactivity was detected in the extracellular matrix around small lymphatic vessels of the skin and heart, respectively. By contrast, absence of immunostaining was observed around lymphatic vessels in the dental pulp. Although the staining was mostly detectable on the non-fibrillar amorphous component of the extracellular matrix, some microfibrils were also immunostained in close proximity to the lymphatic vessel wall. These findings support the concept that small lymphatic vessels may be heterogeneous with respect to the composition of the extracellular matrix around their wall. The observation that it is possible to observe small lymphatic vessels displaying low or no elastin-immunoreactivity in the adjoining matrix militates against the hypothesis that elastic fibers play a pivotal role in the mechanisms that regulate the function of small lymphatic vessels.

Elastin↗

PubMed1994

Lymphatic capillaries of the pig lung: TEM and SEM observations.

Pulmonary lymphatic vessels extend within the connective tissue sheets surrounding airways and blood vessels. Frequently in this location they also border the lobular parenchyma, but not lymphatic vessels have been found within intralobular compartments between blood capillaries and alveoli. The presence and distribution of lymphatic vessels in pulmonary tissue are consistent with an important role for the lymphatic system in the clearance of interstitial fluids in the lung. Pulmonary lymphatic channels have structural characteristics of initial lymphatics; their walls are formed only by an endothelial layer, and no muscular cells are present. A network of anchoring filaments and collagen and elastic fibers surrounds the vessel walls. Because the lung is a mobile organ the tissue undergoes compression and distension during respiratory phases. These modifications could have a role in the mechanisms for lymph formation and flow.

Animals↗

PubMed1994

Inactivation of voltage-dependent calcium current in an insulinoma cell line.

We have studied the mechanism of Ca current inactivation in the beta-cell line HIT-T15 by conventional and perforated patch recording techniques, using two pulse voltage protocols and a combination of current and tail current measurements. In 5 mM Ca, from a holding potential of -80 mV, the maximum current showed a complex time course of inactivation: a relatively fast, double exponential inactivation (tau h1 approximately 12 ms and tau h2 approximately 60 ms) and a very slowly inactivating component (tau > 1 s). The faster component (tau h1) was due to the voltage-dependent inactivation of a low-threshold-activated (LVA), T-type current, which deactivates more slowly (tau approximately 3-5 ms) than the other components (tau approximately 0.2-0.3 ms). The intermediate component (tau h2) was due to the Ca-dependent inactivation of a portion of the high-threshold-activated (HVA) current. A saturating dose of the dihydropyridine (DHP) nifedipine (10 microM) did not affect the LVA current, but inhibited by 68 +/- 5% the transient, Ca-sensitive portion of the HVA current and by 33 +/- 12% the long lasting component. We suggest that three components of the calcium current can be resolved in HIT cells and the main target of DHPs is a HVA current, which inactivates faster than the DHP-resistant HVA component and does so primarily through calcium influx.

Animals↗

PubMed1994

Ameloblastic fibrosarcoma of the jaw: report of five cases.

Five cases of ameloblastic fibrosarcomas (AFS) are reported. The tumour was characterized histologically by a biphasic pattern: the malignant mesenchymal component had the features of an intermediate grade fibrosarcoma in 3 cases, malignant fibrous histiocytoma and osteogenic sarcoma in 2 cases. The epithelial odontogenic component had a benign appearance cytologically. In 1 patient, in the recurrence only the malignant mesenchymal component was present. AFS is a fully malignant tumour, in fact 1 patient died of the tumour after inadequate surgical treatments, and 2 patients had a recurrence after intralesional surgery. The treatment of choice was achieved when surgery with wide surgical margins was performed. As MFH and OGS features are present in the malignant mesenchymal component of this tumour we prefer to use the broad term ameloblastic sarcoma instead of AFS.

Adolescent↗

PubMed1994

Is there a cognitive impairment in MND? A survey with longitudinal data.

Twenty-nine patients affected by motor neuron disease (MND) were investigated with the Raven Progressive Matrices, a test of logical non verbal intelligence, requiring neither motor nor verbal skills. The score distribution of the MND patients did not differ from that of 321 controls. Eleven of these patients were retested after a mean interval of 8.5 months. The resulting differences in the test scores showed that their intellectual performance had not worsened over time. Even allowing for the limitations posed by the use of a single test, these data add to the evidence against systematic cognitive involvement in MND.

Adult↗