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Biomedical subjects

F Greco

Publications and source records attributed to F Greco.

At least 109 records · Page 6Linked to original sources
PubMed1992

[Diagnosis and assessment of thrombolytic efficacy in left atrial thrombosis using transesophageal echocardiography].

In order to evaluate the incidence of atrial thrombosis 17 patients underwent transesophageal echocardiography (TEE). They were referred to our department because of a recent systemic embolic event and we found thrombi located in the left atrial appendage in 14 patients, in 5 cases in the left atrium and in 4 cases in the right atrium. Transthoracic echocardiography showed left atrial masses in 5 patients. Transesophageal echocardiography was more sensitive than transthoracic echocardiography in detecting atrial thrombi. Fifteen patients were treated with thrombolytic therapy using urokinase or rt-PA. To evaluate the efficacy of thrombolysis, we repeated TEE immediately after the infusion and 24 hours later. We observed a reduction of the mass of thrombi in all patients; the effect of therapy was not different 24 hours later. Our study underlines the diagnostic power of TEE in detecting atrial thrombosis and also suggests the use of TEE in the evaluation of the efficacy of thrombolytic therapy.

Aged↗
PubMed1991

Antibodies to hepatitis C virus in patients with mixed cryoglobulinemia.

The prevalence of antibodies to hepatitis C virus (HCVAb) was investigated in 52 unselected patients with mixed cryoglobulinemia and in 84 patients with other systemic immunologic diseases. HCVAb were detected by an enzyme-linked immunosorbent assay, and their specificity was evaluated by a recombinant-based immunoblot assay. The presence of HBV-related markers was investigated in the same samples. HCVAb were found in 54% of mixed cryoglobulinemia patients, and the finding was confirmed by recombinant-based immunoblot assay in all cases. HCVAb and/or HBV markers were present in 70% of the patients. HCVAb seropositivity was significantly more frequent in mixed cryoglobulinemia patients with biopsy-proven liver involvement (P less than 0.01) and with increased serum transaminase levels (P less than 0.01). HCVAb were virtually absent in control patients with other immunologic diseases. These results support the notion that viral agents, i.e., HCV and possibly HBV, have a role in the pathogenesis of mixed cryoglobulinemia patients.

Adult↗
PubMed1991

Fibrin-antibiotic mixtures: an in vitro study assessing the possibility of using a biologic carrier for local drug delivery.

An in vitro study assessing the kinetics of drug release from antibiotic-fibrin seal compounds and the antibacterial efficacy of the delivered drug has been performed. Antibiotic sensitivity and the amount of drug released was measured by means of agar diffusion test. Standard and experimental curves were established for each antibiotic and each bacterial test in order to evaluate the quantities of the drug released during each 24 h period. The reconstitution of lyophilized human fibrin with an aqueous solution containing an antibiotic resulted in only minor modification of the clotting process, with the exception of those solutions containing cefotaxim and mezlocillin which failed to clot altogether and were excluded from further study. The evaluation of the kinetics of elution of the antibiotics from the fibrin clots showed that all of the antibiotics had been almost completely released by 96 h. The delivered amount of each drug was enough to maintain the Minimal Inhibitory Concentration (MIC) until the 4th day of culture for the most of antibiotics, resulting in a prolonged release of the drug.

Anti-Bacterial Agents↗
PubMed1991

Prostaglandins in osteoid osteoma.

Osteoid osteoma is a tumour of bone characterised by pain which is relieved by aspirin and nonsteroidal anti-inflammatory drugs. Very high levels of prostaglandins have been found in the lesion. In five patients with osteoid osteoma, prostaglandin E2 (PGE2) and prostacyclin (PGI2) synthesis in the nidus yielded 1155.6 +/- 496.5 (mean +/- SD) and 245.2 +/- 89.8 pg/mg respectively, values which are 33 and 26 times higher than in fragments of normal bone. The sclerotic bone around the nidus produced both prostaglandins at the same rate as normal bone. In three patients the excretion rate of the major urinary metabolite of systemic PGI1 was reduced to 50% one month after removal of the tumour. The urinary excretion rate of 6-keto-PGF1 alpha, reflecting intrarenal PGI2 synthesis, was not changed after operation. These results offer new insight into the pain mechanism in osteoid osteoma.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

Puromycin aminonucleoside metabolism by glomeruli and glomerular epithelial cells in vitro.

Two puromycin aminonucleoside (PAN) excretion products were purified by HPLC from urine of PAN-treated rats and characterized by nuclear magnetic resonance as N6-dimethyl-3'amino-3'deoxyadenosine (DA-Ado) and N6-methyl-3'amino-3'deoxyadenosine (MA-Ado), respectively, the former corresponding to unmodified PAN. DA-Ado was not a substrate for adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) or xanthine oxidase (XO), while MA-Ado was consecutively converted into hypoxanthine by a mixture of ADA and PNP. A different rate of transformation of DA-Ado and MA-Ado into hypoxanthine by isolated glomeruli was observed and was higher for the monomethylated analogue by a factor of 3 (79% vs. 21%); this was ascribed to the rate-limiting level of a demethylase activity acting on DA-Ado. Furthermore, DA-Ado was not transformed by glomerular epithelial cells in culture, while a little amount of MA-Ado was converted into hypoxanthine after six hours of incubation. In spite of this different metabolic behavior, the same order of cytotoxicity on glomerular epithelial cells in culture was observed for MA-Ado, DA-Ado and commercial PAN. All these molecules induced a dose response inhibition of [3H]thymidine incorporation into DNA after exposure for two hours and a marked alteration of cell viability which was not inhibited by free radical scavengers and deferoxamine. This study provides the first evidence for a glomerular metabolism of PAN and its urinary metabolite MA-Ado involving their transformation via the purine cycle enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Increased prostacyclin biosynthesis in patients with osteoid osteoma.

Osteoid osteoma is a benign osteoid-forming tumor of the bone characterized by pain which is relieved by nonsteroidal anti-inflammatory drugs. Very high levels of prostaglandins have been found in the lesion. In nine patients with osteoid osteoma, prostaglandin E2 (PGE2) and prostacyclin (PGI2) synthesis in explants from the nidus incubated in vitro yielded 947.3 +/- 482.6 (mean +/- SD) and 340.2 +/- 178.1 pg/mg of wet tissue respectively, values 32 and 49 times higher than in fragments of normal bone. In eight patients the excretion rate of the major urinary metabolite of PGI2, i.e. 2,3-dinor-6-keto-PGF1 alpha, was nearly double the control value (499 +/- 93 vs 257 +/- 117 pg/mg of creatinine; mean +/- SD). In six of them, from whom urine was collected 1 month after surgery, urinary 2,3-dinor-6-keto-PGF1 alpha decreased significantly (P less than 0.01) from 487 +/- 100 to 229 +/- 52 pg/mg creatinine. Urinary 6-keto-PGF1 alpha, largely a reflection of intrarenal PGI2 synthesis, was comparable to the control group (4.6 +/- 0.9 vs 4.5 +/- 1.0 ng/h, respectively) and remained unchanged after operation. These results suggest an enhanced PGI2 biosynthesis in vivo in patients with osteoid osteoma. This abnormality of arachidonate metabolism is consistent with enhanced biosynthetic capacity of the tumor in vitro, and is reversible upon its removal.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

The ultrastructure of schwannoma and neurofibroma of the peripheral nerves.

An electron microscopic study of 4 solitary schwannomas and 2 neurofibromas of peripheral nerves was performed with the aim of investigating the debated histogenesis of the two types of lesion. Our observations confirm that solitary schwannoma is composed almost exclusively of cells with characteristics of differentiated Schwann cells, thus providing evidence for a neuroectodermal origin of the tumor. Analysis of the ultrastructure of neurofibroma shows the presence of 3 different types of cells: Schwann-like cells, perineurial-like cells, and fibroblast-like cells. Perineurial-like cells were prevalent in our observations. These findings as well as the many controversial aspects of the origin of neurofibroma could be explained by separating this type of neoplasia into two pathological forms: perineurial and interstitial. Moreover, the numerous differences between solitary schwannoma and neurofibroma allow us to hypothesize a different cellular origin for each tumor. If confirmed by further observations, this would explain the difference in the capacity of the two types of neoplasia to undergo malignant change, an occurrence almost unknown in solitary schwannoma yet relatively common in neurofibroma.

Collagen↗
PubMed1990

Morphological changes in growth-plate cartilage in osteogenesis imperfecta.

We obtained specimens of growth-plate cartilage from four patients with osteogenesis imperfecta. Light microscopy showed structural changes in the tissue and morphological changes in chondrocytes and matrix, particularly in the hypertrophic zone. There were changes in the process of calcification in the primary mineralisation zone of the cartilage. We also found histochemical changes in the matrix glycosaminoglycans (GAGs) in the zones where physiological mineralisation was disturbed and where the trabeculae were interrupted and poorly mineralised. In addition to the known molecular defects in collagen, changes in GAGs and non-collagenous proteins are important factors in the pathogenesis of the disease.

Growth Plate↗
PubMed1990

[Osteoid osteoma of the foot].

We relate about our direct clinical experience on 8 cases of osteoid osteoma localized in the bones of the foot. Some atypical appearances, clinical and roentgenographic, of the osteoid osteoma in this bony district may sometimes cause problems in diagnosis and localization, which are exposed and discussed in this paper. Particularly, we underline the importance of bone scan in the detection of the lesion.

Calcaneus↗
PubMed1989

[Osteoid osteoma: ultrastructural aspects].

The authors take into consideration the ultrastructural aspects of osteoid osteoma and discuss the cellular and subcellular features of this neoplasm. Special attention is given to functional adaptability, which is specific for this type of cell, related to the degree of development of the neoformation.

Calcaneus↗
PubMed1989

[Fibrinolytic activity and adhesive syndromes of the lumbar vertebral canal].

The recent studies, related in medical literature, indicate a reduced activity of fibrinolysis in patients with low back-pain caused by multiple factors (lumbar disc disease, post-laminectomy, post myelography) and suggest a new pathogenetic hypothesis of this disease and new therapeutic implications. The authors conducted a research based on the study of fibrinolysis in patients affected by post-surgical lumbar adhesive syndrome, with the aim of finding, eventually, a relationship between reduced fibrinolytic activity and clinical symptoms. The results are referred and discussed.

Adult↗
PubMed1989

Biological aspects of repair osteogenesis in corticospongy homologous grafts.

An experimental study was carried out aimed at studying the short-term, mid-term and long-term biological features of the incorporation of homologous bone grafts. Homologous cortical and corticospongy grafts of the proximal third of the tibia were implanted in 60 adult New Zealand rabbits, under general anaesthesia. The animals were sacrificed after predetermined periods of time, and the tibia removed for radiographic and histological examination. An analysis of the different phases of the fusion process allowed us to observe the different dynamic evolution of osteogenic repair of cortical as compared to spongy grafts. This could be explained by the different tensile properties of the two types of grafts.

Animals↗
PubMed1989

[Two-dimensional echotomography in the prevention of congenital hip dysplasia].

Examination of the infant hip with real time ultrasonography is spreading and affirming in these last years. It allows accurate and reliable investigation of the anatomic structures which are not visualized on a radiograph, so that it appears of great interest in the early screening of congenital dislocation of the hip (CDH). In this paper, the authors examine and discuss some particular features of the sonograms which are usually employed for the investigation of neonatal hips, attempting to dissolve some doubts and perplexities which commonly come out in the first approach to a new diagnostic image technique. The systematic examination of infant hips with real time ultrasonography promises a decisive improvement in the problem of the early diagnosis of CDH.

Hip Dislocation, Congenital↗
PubMed1989

Scintigraphy in osteoid osteoma: problems related to differential diagnosis.

Scintigraphy is currently the most widely used and most reliable diagnostic instrumental test for the diagnosis of osteoid osteoma. Indications for its use are based on two considerations: 1) the need for preoperative confirmation of a suspected diagnosis based on clinical and radiographic findings; 2) the preoperative differential diagnosis from lesions which, either due to site or to atypical features, can mimic osteoid osteoma and are not easily identified. However, the high sensitivity of the test is associated with low specificity. In order to increase the specificity, the authors use angioscintigraphy and illustrate some cases where this method permitted differential diagnosis with other bone lesions that simulate the clinical and radiographic features of osteoid osteoma.

Adolescent↗
PubMed1988

Experimental investigation into reparative osteogenesis with fibrin adhesive.

An experimental investigation was carried out in order to evaluate the effects of fibrin adhesive on the reparative osteogenesis of bone grafts in the short, medium, and long term. Sixty fully developed New Zealand White rabbits under general anesthesia were grafted with homologous bone tissue in the proximal third of each tibias. Fibrin adhesive was used in one hind limb only. The animals were killed at a predetermined time. Both tibias were removed and subjected to radiographic and histologic analyses. The reparative process was observed and the differences between the fibrin adhesive-treated grafts and the reference group in the first few weeks were determined. No substantial difference was detected in the reparative osteogenetic process of the graft in the animals killed after 2 months.

Animals↗
PubMed1988

Clinical, hematologic, and immunologic cross-sectional evaluation of individuals exposed to human immunodeficiency virus type-2 (HIV-2).

We studied the clinical status and certain hematologic and immunologic parameters in healthy prostitutes from Dakar, Senegal who were seropositive for antibodies to human immunodeficiency virus type-2 (HIV-2). Generalized lymphadenopathy and clinical signs or symptoms similar to those which are seen with human immunodeficiency virus type-1 (HIV-1) infection were not present. Comparison to seronegative prostitutes and minor surgery control patients were made and significant elevations were seen in T8 lymphocytes (p = .03), IgG (p = .0001), and beta 2-microglobulin (p = .03). The mean T4 lymphocyte count in seropositive prostitutes was lower than in seronegative prostitutes (757 vs. 1179, p = .15), but this difference was not statistically significant and appeared to be correlated with age. No significant differences were noted between the seronegative and seropositive prostitutes in lymphocyte stimulation studies to certain mitogens. Antilymphocyte antibodies above background were not present in either population. We conclude that HIV-2 is a sexually transmitted agent that produces immunologic alterations consistent with a persistent viral infection. HIV-2 seropositive prostitutes studied to date do not show clinical signs of immune suppression, as has been described with HIV-1 infection. The pathogenic potential of HIV-2 appears to differ from that of HIV-1, the etiologic agent of the AIDS pandemic.

Adult↗
PubMed1988

Nerve fibres in osteoid osteoma.

Many authors have attempted to explain the mechanism of pain in osteoid osteoma and, in the past, several histological studies have been carried out with the specific aim of verifying the existence of nerve fibres within the tumour. The histochemical procedures based on the affinity of nerves for silver stains have made it possible to demonstrate the presence of fine nerve fibres disposed alongside and around the vessels. An analogous study was conducted to confirm this and to supply further morphological and functional information useful for an understanding of the genesis of pain. The study involved three cases of osteoid osteoma using both traditional histochemical procedures and electron microscopy. The latter, in particular, allowed us to confirm the myelinic nature of the nerve fibres observed under optic microscopy. Based on these observations, the authors present a hypothesis on the function of the nerve fibres in the mechanism of pain stimulation.

Bone Neoplasms↗