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  • 1
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary.  We investigated the pathogenetic relevance of hepatitis C virus (HCV) infection in mixed cryoglobulinemia (MC) with or without complicating B-cell Non-Hodgkin’s lymphoma (NHL) in comparison with other immunological and lymphoproliferative disorders. The following groups of patients were studied: A) 25 patients with MC in 7 cases evolved into B-cell NHL; B) 25 healthy subjects; C) 22 patients with different systemic immune diseases; D) 24 patients with chronic HCV infection without MC; E) 25 patients with B-cell idiopathic NHL. Methods used included: i) Polymerase chain reaction (PCR) for HCV RNA detection in serum and peripheral blood mononuclear cells (PBMC) (uncultured or mitogen-stimulated); ii) Branched DNA (b-DNA) for HCV RNA quantification; iii) HCV genotyping by genotype-specific primers localized in the core region and by hybridization of amplification products of the 5′ untranslated region (5′UTR), obtained with universal primers, using genotype-specific probes. Serum anti-HCV and HCV RNA were detected in 88% and 73% of MC patients, respectively, and in a significantly lower percentage of healthy controls and patients with autoimmune diseases. HCV RNA concentration was significantly lower in supernatants than in corresponding whole sera (p〈0.001). Plus-strand HCV RNA was detected in 81% of peripheral blood mononuclear cell (PBMC) samples and minus-strand in the majority of fresh or mitogen stimulated cells. All MC patients with NHL had HCV RNA sequences in PBMC. HCV genotype 2a/III was detected in MC patients with a prevalence that was significantly higher than in HCV infected patients without MC. Surprisingly, HCV markers (anti-HCV and/or HCV RNA) were found in 32% of patients with idiopathic NHL. These data suggest that HCV infection is involved in the pathogenesis of MC through both direct participation in the immune complex related vasculitis and by triggering the lymphoproliferative disorder underlying the disease. This latter disorder seems to be related to HCV lymphotropism which could also be responsible for the evolution of MC to malignant lymphoma. This study also suggests that HCV infection may be involved in the pathogenesis of idiopathic B-cell NHL through a similar pathogenetic mechanism.
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  • 2
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary.  The possibility of hepatitis B virus (HBV) infection in HBsAg-negative patients has been shown. However, an “inapparent” coinfection by HBV in hepatitis C virus (HCV)-positive patients generally is not taken into account in clinical practice. Mechanisms responsible for resistance to interferon (IFN) have not been completely clarified. The aim of this study was to investigate whether an “inapparent” coinfection by HBV in anti-HCV-positive chronic liver disease patients may influence IFN response. Fourteen anti-HCV positive, HBsAg-negative but serum HBV DNA-positive patients by PCR and 111 anti-HCV-positive, HBsAg-negative and HBV DNA (PCR)-negative patients with chronic hepatitis were treated with 3 MU of recombinant α-2a IFN 3 times weekly for 12 months. Serum HBV DNA and HCV RNA were determined before treatment, after 6–12 months and in coincidence with ALT flare-up by PCR. HBV PCR was performed using primers specific for the S region of the HBV genome and HCV PCR with primers localised in the 5′NC region of HCV genome. IgM anti-HBc was tested using IMx Core-M Abbott assay. By the end of treatment, ALT values had become normal in 4/14 HBV DNA-positive patients (28%), but all “responders” (4/4) relapsed between 2 and 5 months after therapy. All but one patient were HCV RNA-positive before treatment, 6 were also both HBV DNA and HCV RNA-positive during ALT flare-ups. In 5 patients, only HBV DNA and in 3 patients, only HCV RNA was detected when transaminase values increased. All patients remained HBsAg-negative and anti-HCV-positive. IgM anti-HBc was detected both before treatment and during ALT elevation in 3 patients and only during ALT relapse in 3 others. Of the 111 anti-HCV positive, HBsAg-negative and HBV DNA (PCR)-negative patients with chronic hepatitis, a biochemical response to IFN treatment was observed in 54% of the cases. Relapse of ALT values was observed in 47% of the cases during a follow-up of 1 year after treatment. “Inapparent” HBV/HCV coinfection may be implicated in cases of resistance to IFN treatment. In addition, HBV replication may persist in patients in whom HCV replication was inhibited by IFN treatment. The pathogenic role of HBV in liver disease was confirmed by detection of IgM anti-HBc in some cases; the appearance of these antibodies only after IFN treatment suggests that IFN may exert a selective role in favour of HBV. Further studies will show the effect of different treatment schedules. HBV DNA and/or IgM anti-HBc detection with very sensitive methods may be important both as a prognostic factor and as a tool for better understanding interviral relationships and mechanisms involved in multiple hepatitis virus infections.
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  • 3
    ISSN: 1432-0533
    Keywords: Key words Isochromosome 12p ; Immature teratoma ; Brain tumor ; Germ cell tumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An immature teratoma arising in the pineal gland in a 27-year-old male was shown to present an isochromosome 12p as evidenced by cytogenetic and fluorescence in situ hybridization analysis. As i(12p) is characteristic of gonadal germ cell tumors, this case indicates that similar genetic pathways may operate in gonadal and intracranial teratomas.
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 29 (1996), S. 230-235 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: This work proposes a new four-crystal monochromator particularly indicated for applications in the field of high-resolution X-ray diffraction. The monochromator is made of two monolithic crystal elements. The first one is a channel-cut crystal consisting of two symmetrically cut components set in a parallel nondispersive geometry. The second monolithic crystal is composed of two crystal components in a parallel nondispersive geometry but the crystal surfaces are miscut with respect to the diffraction planes. The diffraction geometry for both components of the second monochromator crystal element is the glancing-incidence condition. The peculiar properties of this monochromator are investigated theoretically. An appropriate rotation of the second component of the second monolithic block with respect to the first components corrects the beam deviation caused by the refraction effect. This monochromator system may allow one to obtain highly monochromated and collimated beams with high angular resolution (about 0.01 mrad) and wavelength dispersion of about 4 × 10−5. The intensity reduction of the proposed crystal arrangement in comparison with other monochromators is discussed, including wavelength spread and beam size increase.
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  • 5
    ISSN: 1573-2568
    Keywords: HEPATITIS C VIRUS ; AMINOTRANSFERASES ; LIVER HISTOLOGY ; ASYMPTOMATIC CARRIER
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In this study we aimed to correlate liverhistology and the presence of hepatitis C virus (HCV)viremia, genotype, and quantity of HCV genome in 19positive and 11 RIBA II indeterminate patientspresenting persistently normal ALT values over 24 monthsbefore biopsy. In addition, after biopsy serum ALTvalues were monitored monthly for a mean follow-upperiod of 24.8 months, after which patients werereevaluated for RIBA II and the presence of viremia.Sixteen patients (53%) were serum HCV-RNA-positive; 13of them (68%) were confirmed positive and 3 (27%)indeterminate on RIBA II. Histology of the HCV-RNA-positive patients showed eight cases of CPH (one case ofgenotype 1a; four cases type 1b; three cases type 2),six cases of CAH (three cases type 1b, three cases type2), one case of CLH (type not determined), and one case of normal liver (NL) (type 1b).Histology of the HCV-RNA-negative patients showed fourcases of CPH, one case of CAH, two cases of CLH, andseven cases of NL. During the follow-up period ninepatients (30%) presented slight increases in ALT values(〈2 × N), and in particular, flares of ALT wereobserved four times in the CAH and five times in the CPHpatients, who were all viremic, but never in the NL subjects. These results indicate that subjectspositive on RIBA II, but with persistently normal ALTvalues, had a high probability of being serumHCV-RNA-positive and that almost all these viremicsubjects presented histologic signs of liver disease. Incontrast, RIBA II indeterminate subjects had a moderateprobability of being HCV-RNA-positive, but a number ofthese may present signs of liver disease. In both cases there was no association withgenotype or HCV-RNA serum levels. The other nonviremiccases included subjects with hepatic changes goingtoward resolution or with normal liver in whom hepatic biopsy can be avoided. Only one case was a truecarrier since he was viremic with normal liver andpersistently normal ALT values.
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  • 6
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this work we report on transmission electron microscopy and high-resolution x-ray diffractometry studies of lattice matched AlxIn1−xAs/InP and GayIn1−yAs/InP epilayers grown by molecular beam epitaxy on InP(100) substrates. High-resolution and diffraction contrast electron microscopy measurements show the presence of different contrast zones in the epilayers. The analysis of high-resolution x-ray diffraction measurements and computer simulations ascribe these zones to the presence of a compositional gradient in the epilayers. A comparison among investigated samples grown under slightly different growth conditions combined with an analysis of the crystal defects is presented. Growth-induced small variations in the chemical composition of the epilayer can produce differences in the structural quality of the epitaxial layer. Finally, a few monolayers thick and highly strained film of InAsP, is observed in all investigated samples at the substrate/epilayer interface. The formation of this interface layer is explained by the exchange of As and P during exposure of the InP surface to As4 before the growth. © 1995 American Institute of Physics.
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  • 7
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structural characterization of ZnS epilayers grown by hydrogen transport vapor-phase epitaxy on (100)-oriented GaAs substrates is reported. X-ray-diffraction measurements in both double-axis (DA) and single-axis modes were performed to determine the residual strain tensor and the strain temperature dependence of the epilayer in the range between 25 and 650 °C. From the analysis of the data obtained by DA measurements of several symmetric Bragg reflections at different azimuth angles and several asymmetric reflections recorded in different geometries, an orthorhombic distortion of the ZnS lattice was found. The crystallographic symmetry could be explained by an asymmetric distribution of the misfit dislocation density in the interface plane along the [011] and [01¯1] directions. The temperature dependence measurements of the strain tensor components between room temperature and the growth temperature (650 °C) allowed determination of the thermal misfit between ZnS and GaAs and the linear thermal-expansion coefficient of ZnS. Finally, triple-crystal diffractometry and secondary-ion-mass spectrometry were used to investigate the chemical nature of the ZnS-GaAs interface. The results indicate the presence of an interdiffused ZnS-GaAs interface region, whose occurrence turns out to be associated with the initial defect structure of the substrate surface before the growth. © 1995 American Institute of Physics.
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  • 8
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strained multiple quantum wells of InxGa1−xAs/GaAs were grown by low pressure metalorganic chemical vapor deposition (LP-MOCVD) and characterized by secondary ion mass spectrometry, x-ray diffraction, and optical spectroscopy. The structural analysis demonstrates the excellent control of the interface morphology and composition achieved by MOCVD growth. Temperature dependent optical absorption, photoluminescence, and magnetotransmission were used to evaluate the well-width dependence of the major excitonic properties. The samples show sharp excitonic resonances with distinct excited states evolving into Landau-type excited states in high magnetic field. The well-width dependence of the excitonic eigenstates and of the exciton binding energy as well reproduced by envelope function and variational calculations, also in the presence of external electric field. Finally, nonlinear electro-optic modulation induced by the quantum confined Stark effect is demonstrated in a Schottky diode with extremely low switching threshold. © 1996 American Institute of Physics.
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  • 9
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on a structural study of Si/Ge multilayers grown by molecular-beam epitaxy on (100)-Si substrates. The analyses have been performed by using transmission electron microscopy, high-resolution x-ray diffraction, and secondary-ion-mass spectrometry. The investigated specimens differ in number of periods, period thickness, and in the Si/Ge periods thickness ratio. In particular, we investigate the interdiffusion of the Ge atoms in each superlattice period of the epilayer and in the epilayer as whole. The interdiffusion causes a broadening of the nominal thickness of the Ge layer producing a SixGe1−x alloy. Furthermore, the Ge content in the multilayer periods increases as a function of the growth time, i.e., the superlattice periods close to the sample surface contain more Ge atoms if compared to the periods close to the substrate/superlattice interface. We find two steps in the strain relaxation: (i) In each period the strain energy density is partially reduced by the formation of coherent islands; (ii) at a certain value of the strain energy density the shape of the islands changes and the structures relax partially or completely the accumulated strain energy by nucleation of extended defects. © 1996 American Institute of Physics.
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