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Biomedical subjects

A Marconi

Publications and source records attributed to A Marconi.

At least 19 recordsLinked to original sources
PubMed2006

Complications of percutaneous nephrostomy in the treatment of malignant ureteral obstructions: single-centre review.

PURPOSE: The purpose of this study was to evaluate the incidence and type of complications connected with percutaneous nephrostomy (PCN) deployment by comparing two different techniques. MATERIALS AND METHODS: In the last 3 years, 299 procedures of nephrostomy were performed on 201 patients (93 women, 108 men; mean age 65.7 years, range 32-102 years) at our Institute; all patients were affected by malignancy. In 44 cases (14.72%), patients presented grade IV hydronephrosis and in 255 cases (85.28%) grade II-III hydronephrosis. In 68 patients (23.07%), the procedure was carried out under emergency conditions because of the rapid worsening of renal function. All procedures were carried out in the angiography room, with the patient lying in a prone or prone-oblique position, under ultrasound and fluoroscopic guidance. Access to the pyelocalyceal system (intermediate or lower calices) was performed by using a Seldinger technique in 255/299 cases, or a one-step technique (OST) in 44 procedures when grade 4 hydronephrosis was present. Statistical analysis of results was performed using bilateral tests on proportions as well as chi2 test of independence for contingency tables. RESULTS: We observed no major complications. All in all, the rate of minor complications was 3.01% (9/299 cases): 8/255 (3.13%) cases with the Seldinger technique; 1/44 (2.27%) with OST. We observed 43/299 (14.4%) dislodgements: 32/255 (10.70%) with the Seldinger technique and 11/44 (3,68%) with OST. In 4/299 (1.33%), rupture of the catheter occurred, and in 2/299 (0.67%), kinking occurred (in all cases with OST). From the statistical analysis, we conclude that the examination technique modifies the percentage of complications; in particular, it significantly (p<0.05) influences complications connected with the catheter but not minor complications. In addition, the system of fixing does not affect the percentage of dislodgements. CONCLUSIONS: PCN is a method with a high percentage of technical success with low rate of complications thanks to combined use of sonographic and fluoroscopic guidance for the procedure. The OST technique is indicated for a highly remarkable hydronephrosis and in cases where the catheter is only placed for a short period. The Seldinger technique is carried out in patients with grades II and III hydronephrosis and if the disease is predicted to have a long duration.

Adult↗
PubMed2006

Fate and characterization of circulating tumor cells in a NOD/SCID mouse model of human hepatocellular carcinoma.

There is much debate about the way in which epithelial tumors metastasize. It has been proposed that the bone marrow (BM) acts as a tumor cell reservoir. We injected human hepatocellular carcinoma (HCC) cells (Mahlavu cell line) into the livers, circulation or BM of NOD/SCID mice and circulating tumor cells were quantified. When injected under the Glisson capsule, a primary tumor developed and continuously yielded circulating tumor cells. Liver tumor removal led to a very low level of Mahlavu cells both in blood and BM 30 days later. When Mahlavu cells (cultured or from BM of primary mice femurs) were intravenously injected into mice, the number of cells in the bloodstream (BS) steadily decreased, whereas the BM was not significantly colonized. When Mahlavu cells were directly injected into one femur, the controlateral femur was not colonized. Microscopic analysis and a sensitive PCR assay (<1 Mahlavu cell/nuclear cells) both failed to detect human tumor cells in other organs regardless of injection route. In conclusion, our model strongly supports the hypothesis that HCCs continuously release cells into the BS. However, in sharp contrast with the current hypothesis, the BM is not specifically colonized by tumor cells but could store them at a very low level.

Animals↗
PubMed2003

Naftidrofuryl-driven regulation of endothelial ICAM-1 involves nitric oxide.

Naftidrofuryl is a selective inhibitor of the 5-HT2 receptor expressed on human endothelial cells. This drug has been used over the years to cope with cerebral or peripheral ischemic accidents; however, no clear mechanism of action of this molecule has been highlighted to explain its vascular effects. In the present work, we demonstrate that the involvement of nitric oxide can account for the effects of naftidrofuryl. Indeed, naftidrofuryl potently inhibited the TNF-alpha-triggered increase of intercellular adhesion molecule-1 (ICAM-1) expression as well as stress fiber formation in human umbilical vein endothelial cells (HUVEC). Moreover, naftidrofuryl induced the expression of type II nitric oxide synthase (NOS II) messenger and protein, leading to a noticeable increase in nitric oxide synthesis. Furthermore, using the specific NOS II inhibitor 1400W, we verified that the observed effects of naftidrofuryl were NOS II-dependent. The biology of nitric oxide accounts for the reduction of the vasospasm associated with stroke and the strong inhibition of platelet aggregation. In conclusion, our work provides evidence for the inhibition of leukocyte recruitment by downregulation of CD54/ICAM-1, an additional key factor to be dealt with during thrombotic accidents. Importantly, it also highlights a novel NOS II-dependent mechanism of action for naftidrofuryl.

Cells, Cultured↗
PubMed2003

Expression and function of neurotrophins and their receptors in cultured human keratinocytes.

Whereas nerve growth factor has been extensively studied in human keratinocytes, little is known on the role of other members of the neurotrophin family. We investigated the expression and function of neurotrophins and neurotrophin receptors in cultured human keratinocytes. We demonstrated by reverse transcription-polymerase chain reaction that keratinocytes synthesize neurotrophin-3, brain-derived neurotrophic factor, and neurotrophin-4/5. These cells also express tyrosinase kinase A and C, the nerve growth factor and neuro-trophin-3 high-affinity receptors, respectively. On the other hand, only the truncated extracellular isoform of tyrosinase kinase B, the high-affinity brain-derived neurotrophic factor and neurotrophin-4/5 receptor, is detected in keratinocytes. Moreover, neurotrophin-3, brain-derived neurotrophic factor, and neurotrophin-4/5 proteins are secreted by human keratinocytes at low levels. Keratinocyte stem cells synthesize the highest amounts of nerve growth factor, while they secrete higher levels of nerve growth factor as compared with transit amplifying cells. Neurotrophin-3 stimulates keratinocyte proliferation, where brain-derived neurotrophic factor or neurotrophin-4/5 does not exert any effect on keratinocyte proliferation. Addition of neurotrophin-3 slightly upregulates the secretion of nerve growth factor, whereas nerve growth factor strongly augments neurotrophin-3 release. Ultraviolet B irradiation downregulates nerve growth factor, whereas it augments neurotrophin-3 and neurotrophin-4/5 protein levels. Ultraviolet A irradiation increases the level of neurotrophin-3, whereas it does not exert any effect on the other neurotrophins. Finally, neurotrophins other than nerve growth factor fail to protect human keratinocytes from ultraviolet B-induced apoptosis. This work delineates a functional neurotrophin network, which may contribute to epidermal homeostasis.

Apoptosis↗
PubMed2002

Expression of nerve growth factor-like polypeptides and immunoreactivity related to the two types of neurotrophin receptors in earthworm tissues.

Nerve growth factor (NGF) belongs by sequence homology to the neurotrophins, a family of proteins binding the same p75 receptor and closely related members of the Trk family of receptor tyrosine kinases. Fundamental in the vertebrate nervous system, neurotrophin signals have also been suggested as essential for relatively complex nervous systems occurring in invertebrate species that live longer than Caenorhabditis elegans and Drosophila melanogaster. Mammalian neurotrophins have been found to influence invertebrate neuronal growth. However, there are only a few data on the presence of molecules related to neurotrophin signalling components in invertebrates. Our studies provide evidence that analogues of neurotrophins and neurotrophin receptors are expressed in Eisenia foetida earthworms. In particular, NGF-like and Trk-like immunoreactive proteins are both expressed in the nervous system, whereas p75-like positivity identifies tubular structures associated with dorsal pores that are involved in the earthworm response to mechanical irritation or stress.

Animals↗
PubMed2001

The two PM(2.5) (fine) and PM(2.5-10) (coarse) fractions: evidence of different biological activity.

Recent studies have shown that an increased concentration of environmental particulate matter (PM(10)) is related to many respiratory diseases. One major issue is whether the toxicity of the particles resides in some particular fraction as defined by chemical composition and size. The overall purpose of this study was to compare the in vitro toxicity of coarse (PM(2.5-10)) and fine (PM(2.5)) particulate matter, collected in an urban area of Rome, in relation to their physicochemical composition as assessed by analytic electron microscopy and atomic absorption spectroscopy. In particular, our aim was to evaluate the importance of particle physicochemical components in the induced toxicity. The in vitro toxicity assays used included human red blood cell hemolysis, cell viability, and nitric oxide (NO) release in the RAW 264.7 macrophage cell line. The hemolytic potential has been widely used as an in vitro toxicity screen and as a useful indicator of oxidative damage to biomembranes. We found that human erythrocytes underwent dose-dependent hemolysis when they were incubated with varying concentrations of fine and coarse particles. The hemolytic potential was greater for the fine particles than for the coarse particles in equal mass concentration. However, when data were expressed in terms of PM surface per volume unit of suspension, the two fractions did not show any significant hemolytic differences. This result suggested that the oxidative stress induced by PM on the cell membranes could be due mainly to the interaction between the particle surfaces and the cell membranes. RAW 264.7 macrophage cells challenged with particles showed decreased viability and an increased release of NO, a key inflammatory mediator, and both effects were not dose dependent in the tested concentration range. The fine particles were the most effective and the differences between the two size fractions in inducing these biological effects remained unchanged when the basis of comparison was changed from weight to surface measures. It seemed therefore that these differences relied on the different physicochemical nature of the particles. The main chemical difference between the two fractions resided in a greater abundance of C-rich particles with S traces in the fine fraction. Therefore, we cautiously suggest a role for these particles in the induction of toxicity.

Air Pollutants↗
PubMed2001

Computed tomography and magnetic resonance imaging of pathologic conditions of the middle ear.

Computed tomography (CT) is an excellent technique for demonstrating even small abnormalities of the thin and complex bony structures of the middle ear. For this reason, it is the modality of choice in the study of conductive hearing loss (CHL). However, not every patient complaining of CHL requires a CT study. In fact, established indications encompass complex conditions, such as the complications of acute and chronic otomastoiditis, the postoperative ear in chronic otomastoiditis or in the localization of prosthetic devices, and the assessment of congenital or vascular anomalies. Particularly, the precise extent of bone erosion associated with cholesteatoma is correctly demonstrated by high resolution CT. Conversely, although fistulization through the tegmen tympani or the posterior wall of temporal bone is usually detectable by CT, the actual involvement of meninges and veins are better assessed by magnetic resonance (MR). MR is also indicated when complicated inflammatory lesions are suspected to extend into the inner ear or towards the sigmoid sinus or jugular vein. Neoplasms arising from or extending into the middle ear require the use of both techniques as their combined data provide essential information. Most important data for surgical planning concern the destruction of thin bony structures and the relationships of the lesion with the dura and surrounding vessels. DSA and interventional vascular techniques maintain an essential role in the presurgical work-up and embolization of paragangliomas extended into the middle ear.

Cholesteatoma↗
PubMed2000

Regulation of ICAM-1/CD54 expression on human endothelial cells by hydrogen peroxide involves inducible NO synthase.

Expression of the inducible isoform of nitric oxide synthase (iNOS) is stimulated by cytokines in human epithelial cells. This work indicates that incubation of human umbilical cord endothelial cells with combinations of interleukin-1beta, tumor necrosis factor alpha, and interferon-gamma stimulated the synthesis of iNOS mRNA, as detected by reverse transcriptase-polymerase chain reaction. It is important to note that 50, 100, and 200 microM hydrogen peroxide was able to stimulate iNOS directly. Furthermore, 100 microM H2O2 enhanced synthesis of the oxidation products, nitrite (NO2-) and nitrate (NO3-) at 12 and 36 h. iNOS protein, detected by Western blot analysis, as well as L-citrulline levels, were also increased. When endothelial cell monolayers were incubated for 1 h with 100 microM H2O2 and subsequently with cytokines, iNOS mRNA was further augmented. Under the same conditions, we regularly observed an inhibition (25%) of intercellular adhesion molecule-1 (ICAM-1/CD54) expression. The latter was reversed when the NOS inhibitor N(G)-monomethyl-L-arginine was added, as shown by flow cytometry. These data suggest a specific effect of endogenous hydroperoxides on the biosynthesis and processing of the human endothelial iNOS isoform. We propose that H2O2 induces a temporary NO-dependent modulation of adhesion molecule expression to limit the tissue destruction that accompanies the vascular recruitment of leukocytes.

Cells, Cultured↗
PubMed2000

Autocrine nerve growth factor in human keratinocytes.

Biologically active nerve growth factor (NGF) is synthesised and released by proliferating normal human keratinocytes. NGF up-regulates the expression of NGF mRNA in keratinocytes. Keratinocytes express both the low (p75)- and the high-affinity (TrkA) NGF-receptors, which are located in the basal layer of the epidermis. K252, a specific inhibitor of trk phosphorylation, blocks NGF-induced keratinocyte proliferation, in absence of exogenous NGF. Normal keratinocytes over-expressing TrkA proliferate better than control transfectants, while the NGF mimicking anti-Trk antibody induces an increased keratinocyte proliferation in Trk over-expressing cells as compared to mock transfected keratinocytes. In addition, NGF over-expressing keratinocytes proliferate better than mock transfected cells. K252, by blocking TrkA phosphorylation, induces apoptosis in normal keratinocytes, but not in keratinocytes over-expressing bcl-2. Furthermore, NGF transfected keratinocytes are protected from UV-B-induced keratinocyte apoptosis, by maintaining constant levels of Bcl-2 and Bcl-xL . Taken together these results support the concept of an autocrine survival system sustained by NGF and its high-affinity receptor in human keratinocytes. Because NGF and Trk levels are highly expressed in psoriasis. one could speculate that NGF autocrine system plays a role in the mechanisms associated with this and other hyperproliferative skin conditions, including cancer.

Apoptosis↗
PubMed2000

Expression of a functional inducible nitric oxide synthase in hairy cell leukaemia and ESKOL cell line.

The expression of nitric oxide synthase (NOS) isoforms was investigated in the established ESKOL hairy cell line and in leukemic cells of patients with hairy cell leukemia (HCL). By reverse transcription-polymerase chain reaction (RT-PCR), these cells were found to spontaneously express inducible NOS (iNOS)-specific mRNA, but not endothelial constitutive NOS (ecNOS) mRNA. The iNOS protein was detected by immunofluorescence in the cytoplasm of permeabilized leukemic cells and ESKOL cells, using different anti-iNOS monoclonal antibodies. A protein of 135 kDa was identified by Western blotting in ESKOL and HCL lysates, confirming the presence of an iNOS in these cells. Cytosolic homogenates displayed NOS catalytic activity, as measured by the conversion of 14C-labelled L-arginine into 14C L-citrulline and by detection in situ using the DAF-2DA (diaminofluorescein diacetate) NO-sensitive fluorescent probe. Ligation of CD23 (low affinity IgE receptor) was found to increase iNOS expression in ESKOL and conversely to decrease the percentage of cells undergoing apoptosis, as measured by the percentage of cells expressing annexin V. These results indicate that, as in chronic B cell lymphocytic leukemia cells (B-CLL) a functional iNOS is expressed constitutively in hairy cells that contributes to protecting these tumoral cells from apoptosis.

Amidines↗
PubMed2000

Carboxyfullerenes protect human keratinocytes from ultraviolet-B-induced apoptosis.

Carboxyfullerene, a water-soluble carboxylic acid derivative of a fullerene, which acts as a free-radical scavenger, was investigated as a protective agent against ultraviolet-light-induced damage in human keratinocytes. First, we demonstrate that carboxyfullerene is not cytotoxic for these cells. In addition, this compound significantly reduces the ultraviolet-B-induced inhibition of keratinocyte proliferation and protects keratinocytes from apoptosis caused by ultraviolet B irradiation in a time- and dose-dependent fashion. Furthermore, the percentage of cells with depolarized mitochondria is significantly lower in ultraviolet-B-irradiated keratinocytes pretreated with carboxyfullerene than in cells provided with diluent alone. Carboxyfullerene also protects human keratinocytes from apoptosis induced by exposure to deoxy-D-ribose, a sugar that causes cell death through a pathway involving oxidative stress. On the other hand, ultraviolet B downregulates bcl-2 levels in human keratinocytes, and carboxyfullerene fails to prevent this effect. These results suggest that carboxy- fullerene protects human keratinocytes from ultraviolet B damage possibly via a mechanism interfering with the generation of reactive oxygen species from depolarized mitochondria without the involvement of bcl-2.

Apoptosis↗
PubMed2000

[Concentrations of PM10 and PM2.5 particulate material in the atmosphere of Rome].

Starting from 1993, various monitoring campaigns were carried out in Rome to determine PM10 and PM2.5. Their results are presented here cumulatively, with the aim of obtaining preliminary information on relationships among these size fractions, in various seasonal periods and in two sites with different characteristics (a road site and an urban background site in a public park). Particles were collected on filter and gravimetrically determined. Both PM10 and PM2.5 concentrations show temporal fluctuations with higher values during winter months. Background concentrations are lower than those contemporaneously measured at the road site only to a limited extent (10-17%). The contribution of PM2.5 to PM10 during the winter semester is higher than during the summer one (67 vs. 52%), with no substantial intersite differences.

Air Pollutants↗
PubMed1999

Nerve growth factor protects human keratinocytes from ultraviolet-B-induced apoptosis.

Ultraviolet radiation is a potent inducer of apoptosis, whereas autocrine nerve growth factor protects human keratinocytes from programmed cell death. To evaluate the role of nerve growth factor in the mechanisms of ultraviolet B-induced apoptosis, cultured human keratinocytes were ultraviolet B irradiated following pretreatment with K252, a specific inhibitor of the tyrosine kinase high-affinity nerve growth factor receptor. Here we report that the addition of K252 significantly enhanced keratinocyte apoptosis. We then transfected normal human keratinocytes with pNUT-hNGF. Nerve growth factor overexpressing keratinocytes secreted the highest amounts of nerve growth factor in culture supernatants, were more viable, and had a higher rate of proliferation than mock-transfected cells. Whereas ultraviolet B radiation downregulated nerve growth factor mRNA and protein as well as the tyrosine kinase high-affinity nerve growth factor receptor in normal keratinocytes, it failed to do so in nerve growth factor-transfected cells. Moreover, nerve growth factor overexpressing keratinocytes were partially resistant to apoptosis induced by increasing doses of ultraviolet B at 24 and 48 h. These results indicate that downregulation of nerve growth factor function plays an important part in the mechanisms of ultraviolet B-induced apoptosis in human keratinocytes. In addition, ultraviolet B caused a decrease in BCL-2 and BCL-xL expression in mock-transfected keratinocytes, but not in nerve growth factor overexpressing cells. Finally, nerve growth factor prevented the cleavage of the enzyme poly(ADP-ribose) polymerase induced in human keratinocytes by ultraviolet B. These results are consistent with a model whereby the autocrine nerve growth factor protects human keratinocytes from ultraviolet B-induced apoptosis by maintaining constant levels of BCL-2 and BCL-xL, which in turn might block caspase activation.

Apoptosis↗
PubMed1998

Detection of human herpesviruses 6 and 7 in heart transplant recipients by a multiplex polymerase chain reaction method.

In order to evaluate the possible reactivation of human herpesviruses 6 (HHV-6) and 7 (HHV-7) after heart transplantation, buffy-coat and plasma specimens from 21 transplant patients and 56 healthy blood donors were examined for HHV-6 and HHV-7 DNA by polymerase chain reaction. Human herpesvirus 6 and HHV-7 infection or reactivation has been suggested to play a role in cytomegalovirus disease progression in renal transplant recipients. In the present study, however, no significant difference in the prevalence of HHV-6 and HHV-7 was found between the immunosuppressed and the healthy population; moreover, no viral reactivation was found in the heart transplant recipients.

Blood↗
PubMed1997

The sequence of a 8 kb segment on the right arm of yeast chromosome VII identifies four new open reading frames and the genes for yTAFII145.

We report the sequence of a 8,061 bp fragment of Saccharomyces cerevisiae chromosome VII. Five open reading frames (ORFs) of at least 100 amino acids were identified. Three show similarities to the amino-acid sequence of known gene products. ORF G9374 corresponds to the gene coding for the yTAFII145 protein: a TBP-associated factor whose amino-acid sequence was previously reported (Reese et al., 1994). The remaining ORF does not display similarities to known sequences.

Amino Acid Sequence↗
PubMed1997

1,25-dihydroxyvitamin D3, transforming growth factor beta1, calcium, and ultraviolet B radiation induce apoptosis in cultured human keratinocytes.

Apoptosis is a cellular process of self-directed suicide that plays a key role during morphogenesis and in the maintenance of homeostasis in continuously renewing tissues. Currently, apoptosis is detected mainly by gel electrophoresis of fragmented DNA and by typical ultrastructural features such as cell shrinkage and chromatin condensation. Recently, an in situ technique was developed that allows the detection of the apoptotic process in cells and the quantitation of apoptosis in cell populations. We applied this technique to evaluate the apoptotic process in cultured normal human keratinocytes under basic conditions and after stimulation with factors and agents that are presumed but have never been proved to induce apoptosis in these cells. Apoptosis was analyzed after stimulation with 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], transforming growth factor beta1 (TGFbeta1), calcium, UVB, or tumor necrosis factor alpha (TNFalpha). All these factors except TNFalpha induced apoptosis in human keratinocytes. Whereas UVB and calcium were good apoptogenic stimuli at 6 and 24 h, respectively, the vitamin D derivative and TGFbeta1 induced apoptosis after 5 and 6 d in culture. Apoptosis was also established by DNA fragmentation and electron microscopy. Finally, TUNEL technique showed that the number of apoptotic cells increases slightly (5-10%) from 24 to 144 h even in untreated keratinocytes. Our studies indicate that factors normally involved in the regulation of cell growth and differentiation can also control apoptosis.

Apoptosis↗
PubMed1997

[Benign ulcers of the cecum].

Benign ulceration of the cecum is an uncommon lesion that was originally described by Cruveilhier in 1832. Etiology is unknown and symptomatology not pathognomonic. Pre-operative and intraoperative diagnosis is rare and difficult. Definitive diagnosis is usually obtained by histologic evaluation of the surgical specimen after a right hemicolectomy performed for a suspect of a neoplasm of the cecum. The authors present 7 cases of cecal ulcers and suggest that preoperative diagnosis may be due after a colonoscopy with biopsy. This examination may be performed only in that cases that appear without symptoms of acute abdomen. The authors suggest also to perform right hemicolectomy.

Aged↗