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Biomedical subjects

N Campo

Publications and source records attributed to N Campo.

At least 19 recordsLinked to original sources
PubMed2006

Mechanical behavior of quartz fiber reinforced epoxy resins for teeth restoration.

In this work composite materials, based on quartz fibers and epoxy resins, were employed with the aim to restore damaged teeth. The composite materials were chosen because they show biomechanical features very similar to that of the dentine, the main constituent of the tooth. Extracted teeth were rebuilt with two different restorative procedures: in the first, the composite material was pre-formed in a conical trunk shape abutment (PA) and then bonded to a fiber quartz post with a dental bonder. In the second rebuilt system the abutment was prepared by cross linking the resin on the fiber quartz post with a halogen lamp (CRA). The restored teeth were then mechanically tested and observed with a Scanning Electron Microscope (SEM) with the aim to study the interaction between the reconstructive materials. Wetting and roughness measurements were also carried out in order to study the interface adhesion between the post and the abutments. Characterization analysis evidenced that the CRA restorative procedure improves the adhesion between the substitutive materials and shows higher fracture strength than the PA ones. Anyway both the rebuilt systems are able to support the masticator load. An explanation of the interfacial post-abutment interaction phenomenon is discussed.

Adhesiveness↗
PubMed2004

Serum lamivudine levels in the presence of a lamivudine-resistant HBV mutant.

BACKGROUND/AIMS: Lamivudine efficiently inhibits hepatitis B virus replication and has been used to treat hepatitis B virus recurrence after orthotopic liver transplantation. Although effective, its use is hampered by viral breakthrough due to the appearance of hepatitis B virus drug-resistant strains. Aims of this work were to evaluate the inter- and intra-individual variations of lamivudine serum levels and the effects on the drug levels of the lamivudine-resistant hepatitis B virus mutant infection. METHODS: Serum lamivudine concentration was measured by high-performance liquid chromatography. Polymerase chain reaction analysis and sequencing analysis of the reverse transcriptase area of the polymerase was performed on each sample using specific primers. A polymerase chain reaction-enzyme-linked immunosorbent assay was used to differentiate between wild-type hepatitis B virus and lamivudine-resistant hepatitis B virus strain. RESULTS: Lamivudine serum levels presented minor inter- and intra-individual fluctuations along time, with an important increase at the time of the hepatitis flare-up due to the hepatitis B virus mutant presence. When the wild-type hepatitis B virus briefly reappeared as a mixed population, the titre of lamivudine dropped to below the detection level. CONCLUSIONS: While lamivudine serum levels appears stable when the anti-viral efficacy is fully achieved, important fluctuations are present according to the type of viral population, with a considerable decrease possibly due to the presence of the wild-type virus.

Anti-HIV Agents↗
PubMed2004

Chromosomal constraints in Gram-positive bacteria revealed by artificial inversions.

We used artificial chromosome inversions to investigate the chromosomal constraints that preserve genome organization in the Gram-positive bacterium Lactococcus lactis. Large inversions, 80-1260 kb in length, disturbing the symmetry of the origin and terminus of the replication axis to various extents, were constructed using the site-specific Cre-loxP recombination system. These inversions were all mechanistically feasible and fell into various classes according to stability and effect on cell fitness. The L. lactis chromosome supports only to some extent unbalance in length of its replication arms. The location of detrimental inversions allowed identification of two constrained chromosomal regions: a large domain covering one fifth of the genome that encompasses the origin of replication (Ori domain), and a smaller domain located at the opposite of the chromosome (Ter domain).

Chromosome Inversion↗
PubMed2004

Study of hardness and roughness modification in explanted joint components.

The significant wear of the UHMWPE bearings of explanted knee prostheses is produced mainly by micrometric debris ("third-body" wear) that diffuse toward the mobile metal-polymer interface. Here debris is crushed during the movement producing scratches in the metal and in the polymeric surfaces. Mechanical stress and the biological effects change the physical polymeric properties. In order to evaluate the area of UHMWE bearings submitted to high load stresses, in this work physical investigations are performed on the explanted knee prosthesis. Particularly, the roughness profile analysis (RPA) and the micro-hardness measurements (MHM) resulted suitable for the localisation of the mechanical and biological wear area. In the stressed zone, surface treatments could be applied in order to improve the mechanical resistance of the polymeric material. Particularly, the ion implantation with heavy ions is proposed to enhance the polymeric wear resistance. The Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometry (EDX) and Infrared absorption spectroscopy (FTIR) techniques were also applied and results discussed.

Biocompatible Materials↗
PubMed2001

Clearance kinetics of hepatitis C virus under different antiviral therapies.

Interferon alpha (IFN) has been the standard treatment for hepatitis C virus (HCV) infection. Using the kinetic curves of viral clearance, this study compared three treatment regimes based on IFN alone or in combination with Amantadine or Ribavirin to determine the mechanisms of action and the most suitable way to use these drugs. The early clearance kinetics of HCV were studied in 22 patients with chronic hepatitis C under different antiviral treatments: IFN 3 MU daily (7 pts); IFN 3 MU daily plus Amantadine 200 mg (7 pts); and IFN 3 MU daily plus Ribavirin 1-1.2 gr (8 pts), for 6 months. HCV-RNA was assessed qualitatively and quantitatively on serial samples. The HCV-RNA decay curves suggested a different behaviour of viral clearance induced by the three treatments. While no significant differences were present in the first 6 hours, between 6 to 12 hours Ribavirin induced a rapid decline in the viral load. Amantadine seemed to accelerate it in the third phase (12 to 30 hours) and to provoke a more pronounced viral decline when compared to IFN alone (P < 0.05) or to IFN plus Ribavirin (P < 0.025) (baseline to 30 hours). Thus, while IFN remains the principal antiviral drug, Amantadine upholds the viral decline. Ribavirin, although synergistic with IFN, does not seem to improve the IFN effect during the earliest phase of treatment but probably supports the effects of IFN later on. A new dynamic approach to HCV treatment can therefore be developed.

Adult↗
PubMed2000

Soluble beta2-mu-associated and beta2-mu-free HLA class I heavy chain serum levels in interferon-alpha nonresponder chronic hepatitis C patients. Markers of immune activation, and response to antiviral retreatment.

The serum levels of soluble beta2-mu-associated and beta2-mu-free HLA class I heavy chains were determined in 28 interferon-alpha nonresponder chronic hepatitis C patients retreated with interferon-alpha plus ribavirin and in 70 healthy subjects. The baseline levels of beta2-mu-associated and beta2-mu-free HLA class I heavy chains were significantly higher in patients than in healthy controls (P = 0.001). The levels of beta2-mu-associated HLA class I heavy chains significantly increased in responder patients with respect to nonresponders at the third month of treatment (P = 0.03). At the sixth month of treatment and after 6 months of follow up the levels of beta2-mu-associated HLA class I heavy chains decreased in responder patients and increased in nonresponders. The levels of beta2-mu-free HLA class I heavy chains showed only minor changes during and after treatment. We suggest that the determination of hepatitis C virus RNA levels combined with soluble beta2-mu-associated HLA class I heavy chains, as a marker of immune activation, could identify interferon-alpha non responder chronic hepatitis C patients most likely to respond to a retreatment with interferon-alpha plus ribavirin.

Adult↗
PubMed2000

TT virus infection in haemodialysis patients.

BACKGROUND: The recent discovery of a new parenterally transmitted DNA virus called TT virus (TTV) led us to investigate its prevalence in haemodialysis patients, a high-risk group for blood-borne infection, and to evaluate its role in liver disease. Moreover, we compared the TTV prevalence with the prevalence of other hepatitis virus coinfections. METHODS: Serum samples of 78 patients on maintenance haemodialysis were tested for TTV-DNA, hepatitis G virus (HGV)-RNA, anti-E2, anti-hepatitis C virus (HCV) and HCV-RNA. TTV-DNA was detected by semi-nested PCR using the primers from open reading frame 1 (ORF). HGV-RNA was detected by PCR using specific primers for the NS3 and the 5'-UTR genome regions while anti-E2 were checked by an enzyme immunological test. Anti-HCV was tested by the second generation Chiron RIBA HCV test system. HCV-RNA was evaluated by nested PCR with primers directed to the highly conserved 5' non-coding region of the HCV genome. RESULTS: TTV prevalence in our patients was 19% (15/78) while the prevalence of HCV and HGV infection proved to be 20 and 15.4%, respectively. Among TTV positive patients HGV co-infection was present in five cases (33%), HCV in six cases (39.9%), while HBV co-infection was not present in any of the patients. Only three patients proved positive for all three viruses. ALT levels were normal in most cases (13/15; 86%). In particular, patients with TTV infection alone showed normal ALT levels and HCV coinfection was found in the two patients with moderate ALT increases. CONCLUSIONS: TTV prevalence in haemodialysed patients is significant though the real clinical impact is still unclear. However, we must keep in mind that the epidemiological relevance of TTV infection is probably underestimated due to the impossibility in detecting the corresponding antibody.

Adult↗
PubMed1999

Hepatitis G virus infection in haemodialysis and in peritoneal dialysis patients.

The aim of this study was to detect hepatitis G virus RNA (HGV RNA) and antibodies against the virus envelope protein E2 (anti-E2) in 107 patients either on maintenance haemodialysis (n = 78) or peritoneal dialysis (n = 29) to evaluate the prevalence of HGV infection and to establish its role in liver disease. The total prevalence of HGV infection was of 15.4% among haemodialysis patients, whereas it was 10.3% among peritoneal dialysis patients. HGV RNA was detected in 2 haemodialysis patients (2.6%) and in 3 peritoneal dialysis patients (10.3%). Anti-E2 was found in 10 haemodialysis patients (7.8%), whilst all peritoneal dialysis patients resulted negative. In only 1 patient the alanine aminotransferase level was elevated. This patient underwent liver biopsy that did not reveal evidence of chronic hepatitis. The lower HGV prevalence in haemodialysis patients, when compared with data reported by other European authors, should be related to the lower rate of polytransfused patients in our series (29.5%). Multiple blood transfusions should be considered as the main factor to explain the different prevalence of HGV infection among various European dialysis centres. Detection of both antibody and viraemia is important to establish the real rate of the infection.

Adult↗
PubMed1999

Interferon retreatment in chronic hepatitis C: which patients to choose, and what schedule to use.

UNLABELLED: OBJECTIVE; To evaluate the results of a large cohort of non-responder or relapsing responder patients with chronic hepatitis C retreated with various schedules of interferon (IFN). METHODS: Our study included 276 patients (158 non-responders and 118 relapsing responders) who underwent IFN retreatments. Among the non-responder group, 158 patients underwent further courses of IFN. In particular, 108 patients underwent one course of IFN retreatment, 40 patients underwent two courses, eight patients underwent three courses, and two patients underwent four courses. Regarding the relapsing responder group, the 118 patients were retreated with the same dosage for varying periods. In particular, 50 patients were treated for 6 months, 43 patients for 12 months, and 25 for 24 months. Patients in the subgroups of IFN retreatment were homogeneous as far as age and gender distribution, as well as virological and histological characteristics, are concerned. Qualitative and quantitative HCV-RNA was evaluated at baseline, at the end of treatment and at the last check-up of follow-up. HCV genotype was determined on baseline serum samples. Alanine transaminase (ALT) levels were tested monthly. RESULTS: Long-term biochemical (normal ALT levels) and virological (HCV-RNA negative) response was obtained in 2.6% of non-responder retreated patients, and in 33.9% of relapsing responder retreated patients. Evaluation of response on the basis of the duration of treatment showed that 48%, 19% and 16% of relapsing responder patients retreated for 24, 12 and 6 months, respectively, obtained long-term biochemical and virological response. CONCLUSION: Non-responder patient retreatment is inefficient especially in cirrhotic and/or genotype 1 b patients. IFN retreatment is warranted in relapsing responder patients. In particular, 24-month therapy induces significant long-term biochemical and virological response.

Aged↗
PubMed1999

Chronic hepatitis C. New therapeutic strategies.

BACKGROUND: Aim of this work was to evaluate the early viral decay induced by a daily therapy with alfa-interferon (IFN) and the presence of any synergistic effects of amantadine and ribavirin. METHODS: Twenty patients with a diagnosis of chronic hepatitis C were randomly assigned to receive a course of treatment with: IFN 3MU daily (6 pts); or IFN 3MU daily plus amantadine 200 mg (7 pts): or IFN 3MU daily plus ribavirin 1-1.2 g (7 pts) for 6 months. Blood samples were drown at baseline, at 6, 12, 24, 30 and 48 hrs after the first dose of IFN; at 3, 7, 15 days and at every month. Serum was separated within two hours from the collection and stored at -80 degrees C until use. Viraemia was evaluated qualitatively by the Cobas Amplicor (cut-off 1.00E+02 copies/ml) (Roche Diagnostics, Monza, Milan, Italy) and quantitatively by the Cobas Amplicor Monitor (cut-off 1.00E+03 copies/ml). The HCV genotype was determined for each patient by Inno-LiPA HCV II (Innogenetics, Ghent, Belgium). Liver function tests were evaluated at baseline, at 7 and 15 days and at every month. RESULTS: The analysis of the decay curves showed the presence of a three phase decline in the viraemia. At the end of therapy 7 out of the 20 patients (35%) had normal ALT and undetectable HCV-RNA (2 out of 6 in the IFN group: 33.3%, 3 out of 7: 42.8%; 2 out of 7: 28.6%, in the IFN plus amantadine and IFN plus ribavirin groups respectively). CONCLUSIONS: IFN is the major antiviral effector in the early stage of therapy. The observation of the kinetic curves shows a tendency for the ribavirin to induce a slightly steeper slope of decay in the first 48 hrs, while amantadine seems to induce a slightly deeper abatement of circulating viraemia after 48 hrs.

Journal Article↗
PubMed1998

Chronic hepatitis induced by Jin Bu Huan.

BACKGROUND/AIMS: Jin Bu Huan and other Chinese herbal products are widely taken remedies. They have been developed as a natural alternative to traditional drugs in the treatment of various ailments. Their ability to induce several side effects such as acute hepatitis has already been described. We report a case of chronic hepatic damage following administration of Jin Bu Huan Anodyne tablets. METHODS: The patient, a 49-year-old man, developed biochemical signs of liver damage 2 months after beginning Jin Bu Huan intake (3 tablets/daily) including biopsy-proven chronic hepatitis with moderate fibrosis. Virological, autoimmune, metabolic or other hepatotoxic causes were excluded. Liver function impairment was resolved by discontinuing Jin Bu Huan intake. CONCLUSIONS: This case reinforces the already known hepatotoxicity of this product and should make us think more about the uncontrolled use of alternative products.

Alanine Transaminase↗
PubMed1998

Serum intercellular adhesion molecule-1 and long-term response to IFN-alpha2b therapy in chronic hepatitis C.

We have attempted to correlate the outcome of interferon (IFN) therapy with circulating soluble intercellular adhesion molecule-1 (sICAM-1) and the level of viremia in a sample of patients with chronic hepatitis C virus (HCV) infection. Forty-two patients were studied. Eighteen patients were maintained in long-term remission following IFN therapy, whereas 24 did not respond or relapsed. Serum concentrations of sICAM-1 were measured by enzyme-linked immunoassay. Viremia was measured by branched DNA signal amplification assay. Basal sICAM-1 was significantly higher in long-term responders than in nonresponder/relapsing patients. It was found that very high levels (>1000 ng/ml) were closely associated with long-term clinical response. A quantitative evaluation of viremia in basal conditions, which was significantly lower in long-term responders, gave completely opposite results. During treatment, sICAM-1 concentrations significantly decreased in the group of long-term responders but not in the nonresponders. sICAM-1 reduction was apparent as early as 1 month after treatment started. Serum sICAM-1 may be a useful parameter in evaluating the outcome of patients with chronic hepatitis C infection treated with IFN.

Adolescent↗
PubMed1998

A natural large chromosomal inversion in Lactococcus lactis is mediated by homologous recombination between two insertion sequences.

Comparative analysis of chromosomal macrorestriction polymorphism of the two closely related Lactococcus lactis subsp. cremoris strains MG1363 and NCDO763 revealed the presence of a large inversion covering half of the genome. To determine what kind of genetic element could be implicated in this rearrangement, the two inversion junctions of MG1363 and NCDO763 chromosomes were cloned and characterized. Nucleotide sequence analysis showed the presence of one copy of the lactococcal IS905 element in each junction. Each copy of this element contained the same nucleotide mutation that inactivates the putative transposase. Comparison of the sequences surrounding the insertion sequence demonstrated that the large inversion arose from a single-step homologous recombination event between the two defective copies of the IS905 element. The large inversion presumably conferred no selective disadvantage on strain NCDO763 because this rearrangement did not alter the oriC-terC symmetry of the chromosome and the local genetic environment.

Base Sequence↗
PubMed1997

HCV-RNA levels play an important role independently of genotype in predicting response to interferon therapy.

OBJECTIVE: To evaluate the relationship between hepatitis C virus (HCV)-RNA levels and genotypes in order to establish their potentially predictive role in interferon (IFN) response. DESIGN: To detect HCV genotype at baseline and HCV viraemia levels before and during IFN treatment in three groups of patients with different IFN response. METHODS: Our study included 85 patients with biopsy-proven chronic hepatitis C who underwent IFN therapy at standard schedule (3 MU thrice weekly for 6 months). On the basis of IFN response they were subdivided into three groups as follows: non responders (NR: 27 cases) when alanine aminotransferase (ALT) values (normal value: 0-40 IU) at the end of treatment were abnormal (101.7 +/- 10.4); responders relapsing (RR: 29 cases) when normal ALT values at the end of therapy (28.14 +/- 1.7) increased during follow-up; sustained (long-term) responders (LTR: 29 cases) when ALT values remained normal for at least 12 months of follow-up (ALT values at the end of therapy: 21.8 +/- 1.4). ALT activity was monitored monthly during therapy and each month during 12 months of follow-up. HCV genotype was evaluated before starting treatment whereas HCV-RNA viraemia was checked at baseline and at the 1st and 6th months of therapy. RESULTS: The baseline viral load was higher in the NR group than in the RR and LTR groups independently of genotype; HCV-RNA levels progressively decreased during therapy independently of response but the levels remained significantly higher in the NR group. Genotype 1b was prevalent in the NR group. However, levels of viraemia in genotype 1b LTR patients are significantly lower than in genotype 1b NR patients. CONCLUSION: These results suggest that among viral-related parameters viraemia alone seems to play an important role in predicting response to IFN independently of genotype.

Adult↗