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Biomedical subjects

A Motta

Publications and source records attributed to A Motta.

At least 19 recordsLinked to original sources
PubMed2006

Pharmacokinetic interaction between Amprenavir/Ritonavir and FosAmprenavir on cyclosporine in two patients with human immunodeficiency virus infection undergoing orthotopic liver transplantation.

The pharmacokinetic interaction between highly active antiretroviral therapy (HAART) and immunosuppressive drugs is a critical element in the management of patients with human immunodeficiency virus infection who undergo orthotopic liver transplantation (OLT). We describe the effect of the coadministration of Amprenavir/Ritonavir (APV/r) and FosAmprenavir (FosAPV) on cyclosporine (CsA) concentrations in two patients receiving OLT for end-stage liver disease due to hepatitis C Virus. Patient 1, who was maintained on 300 mg CsA twice a day with a trough concentration (C(trough)) around 250 ng/mL, restarted HAART 12 days after transplantation with 300 mg APV/r twice a day with corresponding APV C(trough) of 5293 ng/mL and RTV C(trough) of 186 ng/mL. Forty-eight hours after initiation of HAART, C(trough) of CsA was 1200 mg/mL, so it was necessary to reduce the CsA dosage 12-fold (50 mg every day) to achieve a therapeutic effect. In Patient 2, who was maintained on 300 mg CsA twice a day and a corresponding C(trough) of 400 ng/mL, HAART was restarted 12 days post-OLT with FosAPV 1400 mg twice a day. After 48 hours C(trough) of CsA was around 600 ng/mL and C(trough) of FosAPV, 1221 ng/mL. In this case it was necessary to reduce the CsA administration 3.5-fold (175 mg every day). In conclusion, therapeutic drug monitoring was necessary to monitor HAART and CsA post-OLT to prevent toxicity due to both therapies. The use of FosAPV without ritonavir boostering is sufficient to maintain adequate CsA blood concentrations, avoiding any event of toxicity.

Adult↗
PubMed2006

Physical-chemical and biological characterization of silk fibroin-coated porous membranes for medical applications.

Membranes in artificial organs and scaffolds for tissue engineering are often coated with biomimetic molecules (e.g., collagen) to improve their biocompatibility and promote primary cell adhesion and differentiation. However, animal proteins are expensive and may be contaminated with prions. Silk fibroin (SF) made by Bombyx Mori silk worms, used as a scaffold or grafted to other polymers, reportedly promotes the adhesion and growth of many human cell types. This paper describes how commercial porous membranes were physically coated with SF, and their physical-chemical properties were characterized by SEM, AFM, tensile stress analysis and dynamic contact angle measurements. The effect of the SF coating on membrane biocompatibility and resistance to bacterial colonization is also examined. The proposed technique yields SF coats of different thickness that strengthen the membranes and make their surface remarkably more wettable. The SF coat is not cytotoxic, and promotes the adhesion and proliferation of an immortalized fibroblast cell line. Similarly to collagen, SF-coated membranes also exhibit a much better resistance to the adhesion of S. epidermidis bacteria than uncoated membranes. These preliminary results suggest that SF is a feasible alternative to collagen as a biomimetic coating for 3D scaffolds for tissue engineering or bioartificial (as well as artificial) prosthesis.

Chemical Phenomena↗
PubMed2005

Fast 3D-EM reconstruction using Planograms for stationary planar positron emission mammography camera.

At the University of Pisa we are building a PEM prototype, the YAP-PEM camera, consisting of two opposite 6 x 6 x 3 cm3 detector heads of 30 x 30 YAP:Ce finger crystals, 2 x 2 x 30 mm3 each. The camera will be equipped with breast compressors. The acquisition will be stationary. Compared with a whole body PET scanner, a planar Positron Emission Mammography (PEM) camera allows a better, easier and more flexible positioning around the breast in the vicinity of the tumor: this increases the sensitivity and solid angle coverage, and reduces cost. To avoid software rejection of data during the reconstruction, resulting in a reduced sensitivity, we adopted a 3D-EM reconstruction which uses all of the collected Lines Of Response (LORs). This skips the PSF distortion given by data rebinning procedures and/or Fourier methods. The traditional 3D-EM reconstruction requires several times the computation of the LOR-voxel correlation matrix, or probability matrix {p(ij)}; therefore is highly time-consuming. We use the sparse and symmetry properties of the matrix {p(ij)} to perform fast 3D-EM reconstruction. Geometrically, a 3D grid of cubic voxels (FOV) is crossed by several divergent 3D line sets (LORs). The symmetries occur when tracing different LORs produces the same p(ij) value. Parallel LORs of different sets cross the FOV in the same way, and the repetition of p(ij) values depends on the ratio between the tube and voxel sizes. By optimizing this ratio, the occurrence of symmetries is increased. We identify a nucleus of symmetry of LORs: for each set of symmetrical LORs we choose just one LOR to be put in the nucleus, while the others lie outside. All of the possible p(ij) values are obtainable by tracking only the LORs of this nucleus. The coordinates of the voxels of all of the other LORs are given by means of simple translation rules. Before making the reconstruction, we trace the LORs of the nucleus to find the intersecting voxels, whose p(ij) values are computed and stored with their voxel coordinates on a hard disk. Only the non-zero p(ij) are considered and their computation is performed just once. During the reconstruction, the stored values are loaded and are available in the random access memory for all of the operations of normalization, backprojection and projection: these are now performed rapidly, because the application of the translation rules is much faster than the probability computations. We tested the algorithm on Monte Carlo data fully simulating the typical YAP-PEM clinical condition. The adopted algorithm gives an excellent positioning capability for hot spots in the camera FOV. To use all of the possible skew LORs in the FOV avoids the software rejection of collected data. Reconstructed images indicate that a 5mm diameter tumor of 37 kBq/cm3, in an active breast with a 10:1 Tissue to Background ratio (T/B), with a 10 min acquisition, for a head distance of 5 cm, can be detected by the YAP-PEM with a SNR of 8.7+/-1.0. The obtained SNR values depend linearly on the tumor volume. The algorithm allows one to discriminate between two hot sources of 5.0 mm diameter if they do not lie on the same axis. The YAP-PEM is now in the assembly stage.

Algorithms↗
PubMed2005

The healing of confined critical size cancellous defects in the presence of silk fibroin hydrogel.

In vitro and in vivo behaviour of an injectable silk fibroin (SF) hydrogel was studied through osteoblast cultures and after implantation in critical-size defects of rabbit distal femurs. A commercial synthetic poly(D,L lactide-glycolide) copolymer was used as control material. In vitro biocompatibility was evaluated by measuring LDH release, cell proliferation (WST1), differentiation (ALP, OC), and synthetic activity (collagen I, TGF ss1, IL-6). Bone defect healing rate and quality of the newly formed bone inside the defects were determined in vivo by measuring trabecular bone volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), mineral apposition rate (MAR) and bone formation rate (BFR/B.Pm). In vitro tests indicated that both materials significantly increased cell proliferation in comparison with the negative control. A significant increase in the TGF-beta1 level was found for SF hydrogel in comparison with the control material and negative control. Both materials promoted bone healing when used to fill critical size defects in rabbit femurs. The new-formed bone of the SF hydrogel treated defects showed significantly higher BV/TV, Tb.Th, MAR and BFR/B.Pm and lower Tb.Sp values in comparison with the control gel. At 12 weeks the re-grown bone of the SF hydrogel-treated defects appeared more similar to normal bone than that of the control synthetic polymeric material-treated defects, except for the Tb.N value that differed significantly from that of normal bone (p<0.05). MAR and BFR/B.Pm presented significantly (p<0.05) higher values for SF hydrogel-treated defects in comparison with controls treated with a synthetic polymeric material, confirming that SF hydrogel accelerated remodelling processes.

Animals↗
PubMed2005

A 700 MHz 1H-NMR study reveals apoptosis-like behavior in human K562 erythroleukemic cells exposed to a 50 Hz sinusoidal magnetic field.

PURPOSE: To study cell damage and possible apoptosis in K562 human erythroleukemic cells exposed for 2 h to an extremely low frequency (ELF) 50 Hz sinusoidal magnetic field with a magnetic induction of either 1 or 5 mT using high resolution proton nuclear magnetic resonance (1H-NMR) spectroscopy. MATERIALS AND METHODS: One-dimensional 1H-NMR spectra were obtained on whole K562 cells and perchloric acid extracts of these cells. In addition, two-dimensional 1H-NMR spectra were also acquired. Cell damage was examined by lactate dehydrogenase release and changes in cell growth were monitored by growth curve analyses, bromodeoxyuridine incorporation and Ki67 antigen localization. Cell death (necrosis and apoptosis) were also studied by using the chromatin dye Hoechst 33258. RESULTS: The variations in numerous metabolites observed with 1H-NMR reveal apoptosis-like behavior in response of K562 cells to ELF fields. CONCLUSION: 1H-NMR can be extremely useful in studying the effects of ELF fields on cells. In particular, the variations in metabolites which suggest apoptosis-like behavior occur when the cells are not identifiable as apoptotic by more traditional techniques.

Apoptosis↗
PubMed2005

Clinical and histological study of a xenogenic bone substitute used as a filler in postextractive alveolus.

AIM: The development of oral implant techniques and the demand for the treatment of increasingly complex cases have drawn the attention of researchers and clinicians towards those systems and materials able to promote bone regeneration. The aim of this paper is to evaluate the clinical behavior and in particular the resorption times of the material used as a filler in postextractive alveolus with the intent of preserving the ridge volume, a prerequisite for successive insertion of osteointegrated fixtures. METHODS: A group of 12 patients, aged between 30-40 years, have been selected at the Oral Surgery Unit of the San Giovanni Calibita Hospital in Rome. They all required an endosseous implant following the loss of a dental element due to radicular fracture of periodontal pathology. The grafting material used is OsteoBiol Putty, an antigen-free bone paste composed of 80% granulated mix and 20% pure collagen. RESULTS: The results emerging from the histological analysis show that 3 months after insertion of this osteoconductive material in the receiving site it can no longer be detected in the samples collected and it has been completely substituted by trabecular bone tissue. CONCLUSIONS: The conclusion is drawn that the heterologous material used in this study shows excellent manageability allowing the operator to easily and accurately remove and shape it in the receiving site.

Adult↗
PubMed2004

Italian version of the Chicago multiscale depression inventory: translation, adaptation and testing in people with multiple sclerosis.

Depression is the commonest psychiatric disturbance in people with multiple sclerosis (MS), with prevalence higher than in the general population and other chronic diseases. However, accurate assessment of depressive symptoms can be biased by somatic symptoms which are part of both MS and depression. We translated and adapted into Italian the Chicago multiscale depression inventory (CMDI) and assessed its acceptability, internal consistency and test-retest reliability in 213 MS outpatients and 213 individually matched healthy controls. The questionnaire was also tested in 32 people with major depression. Acceptability, internal consistency, and test-retest reliability were good overall. We found greater odds for depressive symptoms in people with MS than healthy controls, with highest odds ratio for somatic symptoms (vegetative subscale). The Italian CMDI is characterized by good acceptability, internal consistency, and test-retest reliability. These findings support the use of the CMDI in Italian subjects with MS to screen for and follow depressive symptoms.

Adolescent↗
PubMed2004

Endothelialization of a non-woven silk fibroin net for use in tissue engineering: growth and gene regulation of human endothelial cells.

We have previously shown that a biomaterial consisting of a non-woven fibroin net produced from silk (Bombyx mori) cocoons is an excellent scaffolding material for a wide variety of human cells of different tissue types. Endothelialization must take place for a biomaterial to be successful after implantation. Therefore, primary human endothelial cells and the human endothelial cell lines, HPMEC-ST1.6R and ISO-HAS-1, were examined for adherence and growth patterns on the fibroin nets by confocal laser scanning microscopy after vital staining of the cells and by electron microscopy. Endothelial cells adhered and spread along individual fibers of the nets and did not fill the gaps between individual fibers. Higher attachment and growth coverage was obtained if nets were first coated with gelatin, fibronectin or collagen type I. Proinflammatory markers of endothelial cells on the fibers exhibited a non-activated state and LPS-stimulated cells exhibited activation of these markers. Furthermore, a typical PECAM-1 localization at cell-cell contacts was observed. Scanning electron microscopic examination of fibroin nets after removal of cells did not demonstrate any changes to the fibroin structure. HUVEC and HDMEC on fibroin nets embedded in collagen type I gels formed microvessel-like structures. Thus, silk fibroin nets are a highly endothelial cell-compatible scaffolding material that support the growth, normal and inducible cell functions and angiogenesis potential of human endothelial cells in vitro similar to that observed in vivo.

Animals↗
PubMed2004

Phleum pratense pollen starch granules induce humoral and cell-mediated immune responses in a rat model of allergy.

BACKGROUND: Timothy grass (Phleum pratense) pollen allergens are an important cause of allergic symptoms. However, pollen grains are too large to penetrate the deeper airways. Grass pollen is known to release allergen-bearing starch granules (SG) upon contact with water. These granules can create an inhalable allergenic aerosol capable of triggering an early asthmatic response and are implicated in thunderstorm-associated asthma. OBJECTIVE: We studied the humoral (IgE) and bronchial lymph node cells reactivities to SG from timothy grass pollen in pollen-sensitized rats. METHODS: Brown-Norway rats were sensitized (day 0) and challenged (day 21) intratracheally with intact pollen and kept immunized by pollen intranasal instillation by 4 weeks intervals during 3 months. Blood and bronchial lymph nodes were collected 7 days after the last intranasal challenge. SG were purified from fresh timothy grass pollen using 5 microm mesh filters. To determine the humoral response (IgE) to SG, we developed an original ELISA inhibition test, based on competition between pollen allergens and purified SG. The cell-mediated response to SG in the bronchial lymph node cells was determined by measuring the uptake of [3H]thymidine in a proliferation assay. RESULTS: An antibody response to SG was induced, and purified SG were able to inhibit the IgE ELISA absorbance by 45%. Pollen extract and intact pollen gave inhibitions of 55% and 52%, respectively. A cell-mediated response was also found, as pollen extract, intact pollen and SG triggered proliferation of bronchial lymph node cells. CONCLUSIONS: It was confirmed that timothy grass pollen contains allergen-loaded SG, which are released upon contact with water. These granules were shown to be recognized by pollen-sensitized rats sera and to trigger lymph node cell proliferation in these rats. These data provide new arguments supporting the implication of grass pollen SG in allergic asthma.

Allergens↗
PubMed2004

Fibroin hydrogels for biomedical applications: preparation, characterization and in vitro cell culture studies.

Silk fibroin hydrogels prepared either by treating a 2% (w/v) silk fibroin aqeuous solution at 4 degrees C (thermgel) or by adding 30% (v/v) of glycerol (glygel), were characterized by using Environmental Scanning Electron Microscopy (ESEM), Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Thermogravimetrical Analysis (TGA) and molecular weight determination. The preparation procedure affected morphology and molecular weight of hydrogels, with no or negligible differences being displayed by FT-IR and DSC analyses. While thermgel presented a well uniform porous structure, the morphology of glygel appeared to be non-porous and heterogeneous. Glygel presented lower water content and lower degradation temperatures, associated with the presence of glycerol but likely also to less-organized protein structures. Cytoxicity tests with human osteoblast-like cells indicated that both gels were not cytoxic, while cell cultures pointed out a faster cell proliferation on glygel and a higher cell activation and differentiation on thermgel. These gels could be used as scaffolds able to promote in situ bone regeneration.

Animals↗
PubMed2003

Lupus vulgaris developing at the site of misdiagnosed scrofuloderma.

Cutaneous tuberculosis is a rare form of extrapulmonary tuberculosis primarily occurring in developing countries. The recent increase in the incidence of tuberculosis, especially due to human immunodeficiency virus (HIV) infections, has led to a resurgence of extrapulmonary forms of this disease. We describe a case of lupus vulgaris in a 33-year-old woman who had a 5-year history of a slowly growing plaque on her neck. The lesion was located at the site of surgery repairing the scar resulting from the incision of a subcutaneous abscess during childhood. This lesion was misdiagnosed as bacterial abscess. Histopathologic examination of the plaque revealed non-caseating tuberculoid granulomas consisting of lymphocytes, epithelioid and giant cells. Staining for acid-fast bacilli and culture from biopsied tissue was negative. Polymerase chain reaction (PCR) for detection of Mycobacterium tuberculosis DNA, performed on a skin biopsy specimen, was positive. A diagnosis of lupus vulgaris developing at the site of a previous misdiagnosed scrofuloderma was made. Conventional antitubercular therapy with rifampicin, isoniazid and ethambutol was administered for 6 months, resulting in resolution of the lesion.

Adult↗
PubMed2002

Comparison of two brief neuropsychological batteries in people with multiple sclerosis.

BACKGROUND: We compared two brief neuropsychological batteries devised to assess people with multiple sclerosis (MS) and used them to assess the relationship between cognitive impairment and dinical characteristics. METHODS: We administered either the Brief Repeatable Battery of Neuropsychological Tests (BRBNT) or the Screening Examination for Cognitive Impairment (SEFCI) to 213 consecutive MS outpatients and 213 individually matched controls. RESULTS: Administration times were longer for BRBNT than SEFCI, for MS and controls (p=0.001). People with MS had lower scores in all individual tests than controls (p<0.001, BRBNT and SEFCI). By the criterion of poor performance on one or more tests, the sensitivity of BRBNT was 41.9% and that of SEFCI 31.5%. The corresponding figures by poor performance on two or more tests were 16.2% for BRBNT and 18.5% for SEFCI. The Buschke Selective Reminding and Paced Auditory Serial Addition were the tests best discriminating between people with MS and controls for BRBNT, and the Symbol Digit Modalities test for SEFCI. The only clinical variable independently associated with impaired performance on these batteries was EDSS. CONCLUSIONS: Both cognitive batteries were well accepted and easy to administer. Administration time for SEFCI was significantly shorter than for BRBNT; however, alternative forms for serial evaluation are available only for BRBNT. The BRBNT was slightly more sensitive in detecting impairment by the criterion of poor perfomance on one or more tests. EDSS score was the only clinical variable independently associated with cognitive impairment

Adolescent↗
PubMed2002

Potentiation of carbon tetrachloride hepatotoxicity by pentosan polysulfate in rats.

Few data are available in the literature regarding the effect of pentosan polysulfate (PPS) on normal and fibrotic rat livers. In addition, the combination of PPS and carbon tetrachloride (CCl4) has not been studied so far. The objective of this study was to assess the effect of PPS on rat livers treated or not with CCl4 for the induction of liver fibrosis. The study consisted of four stages: 1) hepatic fibrosis induction with CCl4 (N = 36 rats); 2) evaluation of the effect of PPS on CCl4-induced hepatic fibrosis (N = 36 rats); 3) evaluation of the effect of higher doses of PPS in combination with CCl4 (N = 50 rats); 4) evaluation of the presence of an enzymatic inductor effect by PPS (N = 18 rats) using the sodium pentobarbital test which indirectly evaluates hepatic microsomal enzyme activity in vivo. Adult (60 to 70 days) male Wistar rats weighing 180 to 220 g were used. All animals receiving 0.5 ml 8% CCl4 (N = 36) developed hepatic fibrosis, and after 8 weeks they also developed cirrhosis. No delay or prevention of hepatic fibrosis was observed with the administration of 5 mg/kg PPS (N = 8) and 1 mg/kg PPS (N = 8) 1 h after the administration of CCl4, but the increased hepatotoxicity resulting from the combination of the two substances caused massive hepatic necrosis in most rats (N = 45). PPS (40 mg/kg) alone caused hepatic congestion only after 8 weeks, but massive hepatic necrosis was again observed in association with 0.5 ml CCl4 after 1 to 4 weeks of treatment. Unexpectedly, sleeping time increased with time of PPS administration (1, 2, or 3 weeks). This suggests that PPS does not function as an activator of the hepatic microsomal enzymatic system. Further studies are necessary in order to clarify the unexpected increase in hepatotoxicity caused by the combination of CCl4 and high doses of PPS, which results in massive hepatic necrosis.

Animals↗
PubMed2001

The relationship between 1H-NMR mobile lipid intensity and cholesterol in two human tumor multidrug resistant cell lines (MCF-7 and LoVo).

The high resolution proton nuclear magnetic resonance (1H-NMR) spectra of two different cell lines exhibiting multidrug resistance (MDR) as demonstrated by the expression of the well-known energy-driven, membrane-bound 170 kDa P-glycoprotein pump known as Pgp were investigated. In particular, the mobile lipid (ML) profile, and the growth and biochemical characteristics of MCF-7 (human mammary carcinoma) and LoVo (human colon adenocarcinoma) sensitive and resistant tumor cells were compared. The results indicate that both MCF-7 and LoVo resistant cells have a higher ML intensity than their respective sensitive counterparts. However, since sensitive and resistant cells of each pair grow in the same manner, variations in growth characteristics do not appear to be the cause of the ML changes as has been suggested by other authors in non-resistant tumor cells. In order to investigate further the origin of the ML changes, lipid analyses were conducted in sensitive and resistant cell types. The results of these experiments show that resistant cells of both cell types have a greater amount of esterified cholesterol and saturated cholesteryl ester and triglyceride fatty acid than their sensitive counterparts. From a thorough analysis of the data obtained in this paper utilizing numerous techniques including biological, biophysical and biochemical ones, it is hypothesized that cholesterol and triglyceride play a pivotal role in inducing changes in NMR ML signals. The importance of these lipid variations in MDR is discussed in view of the controversy regarding the origin of ML signals and the paramount role played by the Pgp pump in resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Kinase recognition by calmodulin: modeling the interaction with the autoinhibitory region of human cardiac titin kinase.

Calmodulin (CaM)-protein interactions are usually described by studying complexes between synthetic targets of ca 25 amino acids and CaM. To understand the relevance of contacts outside the protein-binding region, we investigated the complex between recombinant human CaM (hCaM) and P7, a 38-residue peptide corresponding to the autoinhibitory domain of human cardiac titin kinase (hTK). To expedite the structure determination of hCaM-P7 we relied upon the high degree of similarity with other CaM-kinase peptide complexes. By using a combined homonuclear NMR spectroscopy and molecular modeling approach, we verified for the bound hCaM similar trends in chemical shifts as well as conservation of NOE patterns, which taken together imply the conservation of CaM secondary structure. P7 was anchored to the protein with 52 experimental intermolecular contacts. The hCaM-P7 structure is very similar to known CaM complexes, but the presence of NOE contacts outside the binding cavity appears to be novel. Comparison with the hTK crystal structure indicates that the P7 charged residues all correspond to accessible side-chains, while the putative anchoring hydrophobic side-chains are partially buried. To test this finding, we also modeled the early steps of the complex formation between Ca(2+)-loaded hCaM and hTK. The calculated trajectories strongly suggest the existence of an "electrostatic funnel", driving the long-range recognition of the two proteins. On the other hand, on a nanosecond time scale, no intermolecular interaction is formed as the P7 hydrophobic residues remain buried inside hTK. These results suggest that charged residues in hTK might be the anchoring points of Ca(2+)/hCaM, favoring the intrasteric regulation of the kinase. Furthermore, our structure, the first of CaM bound to a peptide derived from a kinase whose three-dimensional structure is known, suggests that special care is needed in the choice of template peptides to model protein-protein interactions.

Amino Acid Sequence↗
PubMed2001

Nitric oxide synthase activity in the splanchnic vasculature of patients with cirrhosis: relationship with hemodynamic disturbances.

BACKGROUND/AIMS: It has been demonstrated that an overproduction of nitric oxide plays an important role in the pathogenesis of the hyperdynamic circulation exhibited by cirrhotic patients. Nevertheless, evidence is supported by studies performed in experimental models or by indirect measurements in humans. The purpose of this study has been to evaluate nitric oxide production in splanchnic vasculature of patients with cirrhosis and to investigate its possible relationship with systemic and splanchnic hemodynamics. METHODS: Nitric oxide synthase (NOS) activity was measured in hepatic artery and portal vein tissues of nine cirrhotic patients. Samples were obtained during liver transplantation. Control samples were obtained simultaneously from the corresponding tissues of the liver donors. Hemodynamic parameters were determined with Doppler ultrasonography. RESULTS: NOS activity was significantly higher in hepatic artery of cirrhotic patients than in controls (8.17 +/- 1.30 vs 4.57 +/- 0.61 pmoles/g of tissue/min, P < 0.05). Patients with ascites showed a higher hepatic artery NOS activity than patients without ascites. Highly significant correlation was observed between cardiac output and hepatic artery NOS activity as well as between portal blood flow and hepatic artery NOS activity. CONCLUSIONS: The present study demonstrates an enhanced production of nitric oxide in the splanchnic vasculature of patients with cirrhosis.

Adult↗
PubMed2001

A combined XPS-SEM/EDX investigation on explanted UHMW polyethylene acetabular cups: possible role of silicon traces in the wear debris.

An investigation was started aimed at a better understanding of the complex phenomena leading to chemical degradation and morphological deterioration of UHMW polyethylene cups in total hip prostheses. Analysis was performed on retrieved implants which needed revision due to inflammation and pain problems. Preliminary results obtained by parallel XPS and SEM/EDX experiments gave evidence, for the first time, that silicon traces are involved in the process of particle formation and segregation onto the surface of the cups. The extent of modification of the surface chemical composition of cups and the process of particle segregation seem to be correlated to both the implant time and to some particular features of patient (age, activity, style of life, etc.). Investigation on a large number of samples is in progress in order to test this hypothesis. The results obtained so far confirmed the potential of surface spectroscopies (XPS) in biomaterial investigations.

Journal Article↗