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Biomedical subjects

A Vallejo

Publications and source records attributed to A Vallejo.

At least 19 recordsLinked to original sources
PubMed2006

Experimental design to optimise the analysis of organic volatile compounds in cow slurry by headspace solid-phase microextraction-gas chromatography-mass spectrometry.

The headspace solid-phase microextraction (HS-SPME) of some odorous organic compounds [volatile fatty acids (VFAs), phenols and indoles] from animal wastes was optimised using an experimental design approach. The variables affecting the HS-SPME process studied were as follows: type of fibre, pH of the slurry (3-7), addition of sodium chloride (0-1 mol L(-1)), sample volume (10-30 mL), exposure time (10-30 min), exposure temperature (25-50 degrees C), desorption time (3-10 min) and desorption temperature (230-310 degrees C). As for the sorbent, three different types of fibres were studied: 50/30 microm divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS), 100 microm PDMS and 85 microm CAR/PDMS. Methylation VFAs was observed when fibres containing PDMS were used. The analytes studied in the optimisation procedure were acetic acid, propanoic acid, butanoic acid, 3-methylbutanoic acid, pentanoic acid, phenol, 4-methylphenol, 4-ethylphenol, indole and skatole (3-methylindole). In order to study the influence of the variables on the responses of the compounds, a Plackett-Burman design was built using the Unscrambler program. The optimisation was carried out using real samples. In order to take into account the matrix effect on the calibration curves, standard solutions were prepared using a purged cow slurry free from the analytes of interest. Repeatability within and among days, accuracy and detection limits were calculated from these calibration curves.

Animals↗
PubMed2006

Influence of hepatitis C and hepatitis G virus co-infection on viral and cellular dynamics in patients infected with human immunodeficiency virus following interruption of highly active anti-retroviral therapy.

This study describes the influence of hepatitis C virus (HCV) and hepatitis G virus (HGV) co-infection on CD4 cell count decline and plasma human immunodeficiency virus (HIV) viral load in HIV-infected patients during a 1-year period following interruption of highly active anti-retroviral therapy (HAART) guided by CD4 count. CD4 cell count decline and plasma HIV viral load did not differ between HIV mono-infected patients and those patients co-infected with HCV and HGV. HCV genotype 1 had no apparent influence on the cellular and viral dynamics in HIV-infected patients compared with other HCV genotypes, although the unbalanced groups make larger studies desirable.

Adult↗
PubMed2004

Analysis of quasispecies in the viral 5' untranslated region of hepatitis C virus to evaluate ribavirin mutagenic effect in patients receiving ribavirin and interferon-alfa.

In the study presented here the ribavirin mutagenic effect was investigated by analyzing quasispecies in the viral 5' untranslated region of hepatitis C virus in six patients with chronic infection who started interpheron-alpha and ribavirin therapy. A remarkable mutation rate during treatment was found in only one individual. This patient had a sustained response and harbored a type 3a virus strain. The different mutated clones in this patient demonstrated no apparent close relationship that could suggest lack of selection pressure by ribavirin. The mutations were located within the loops of subdomains IIIb and IIId of the internal ribosomal entry site. This is an interesting initial finding that needs to be substantiated in a larger trial.

5' Untranslated Regions↗
PubMed2004

Thymic volume is associated independently with the magnitude of short- and long-term repopulation of CD4+ T cells in HIV-infected adults after highly active antiretroviral therapy (HAART).

Age is one of the main factors involved in the rapidity and the magnitude of CD4(+) T cell repopulation in human immunodeficiency virus (HIV)-infected patients on highly active antiretroviral treatment (HAART). Improved thymic function has been suggested as the main factor associated with CD4(+) T cell restoration after HAART. This work was undertaken to determine, among host factors, the predictor variable at baseline involved in the magnitude of short- and long-term recovery of CD4(+) T cells after HAART. HIV-RNA levels and CD4(+) T cell numbers were determined in 54 HIV-infected adults at baseline and at weeks 4, 12, 48 and 96 after HAART. T cell subpopulations were determined by flow cytometry, thymic volume by computed tomography, T cell receptor excision circle (TREC)-bearing cells by quantitative polymerase chian reaction (PCR) and interleukin (IL)-7 levels by enzyme linked immunosorbent assay at baseline. The phenotype of patients' isolates was determined by infecting GHOST cells expressing CCR5 and CXCR4. The possible interference of phenotype with thymic function was also analysed. Baseline thymic volume was associated independently with the magnitude of short- and long-term recovery of CD4(+) T cells after HAART, despite the patients' viral phenotype. The measurement of thymic volume before therapy may predict the magnitude of T cell increase. This result could have important clinical implications not only in HIV-infected patients, but also in other scenarios of T cell depletion such as bone marrow transplantation and chemotherapy.

Adult↗
PubMed2001

Changes in the rate of genotypic resistance to antiretroviral drugs in Spain.

Genotypic resistance to antiretroviral drugs was examined in 684 individuals attending 18 outpatient clinics distributed across Spain in June 2000. Compared with similar surveys conducted before 1998, the prevalence of resistance to nucleosides has declined significantly among naive chronic HIV carriers. In contrast, resistance among pre-treated patients has increased; resistance to all three drug families having been recognized in nearly a quarter of patients.

Anti-HIV Agents↗
PubMed1999

Absence of human T-lymphotropic virus type I tax sequences in a population of normal blood donors in the Baltimore, MD/Washington, DC, area: results from a multicenter study.

BACKGROUND: It was reported recently that sequences corresponding to the human T-lymphotropic virus type I (HTLV-I) tax gene were detected in peripheral blood mononuclear cells from 8 to 11 percent of healthy blood donors without detectable antibodies to HTLV-I. A multicenter blind study was conducted to determine if these results could be independently confirmed. STUDY DESIGN AND METHODS: Specimens were collected from 100 anti-HTLV-I-negative healthy blood donors and from 11 anti-HTLV-I- or anti-HTLV-II-positive individuals. All samples were coded and distributed to each of four independent testing laboratories for polymerase chain reaction analysis to detect sequences of the HTLV-I or HTLV-II tax gene, using detailed procedures specified by the laboratory reporting the original observation. Each laboratory also tested a dilution panel of a plasmid containing HTLV-I tax to determine the analytical sensitivity of the procedure. RESULTS: The analytical sensitivity of the screening methods permitted detection of as few as 1 to 10 copies of the tax gene. However, HTLV-I tax sequences could not be detected in any of the anti-HTLV-I-negative blood donors at more than one test site. CONCLUSION: HTLV-I tax sequences appear not to be present in this population of 100 blood donors negative for anti-HTLV-I.

Adult↗
PubMed1998

Tropism, coreceptor use, and phylogenetic analysis of both the V3 loop and the protease gene of three novel HIV-1 group O isolates.

HIV-1 has been subdivided into two groups, M and O, based on phylogenetic analysis. To better understand the pathogenesis of group O viruses, we studied biologic and genetic characteristics of two primary isolates from Spain, ES1158.1 and ES1159.1, and one from the United States, MD.1. After viral isolation, we studied the replication kinetics in peripheral blood mononuclear cells (PBMCs) and macrophages, as well as in different cell lines. All three isolates could replicate in both PBMCs and macrophages. Because no syncytium formation was detected in the MT-2 cell line, viruses were classified as non-syncytium inducing (NSI). All three isolates used the CCR5 coreceptor for entry into the human osteosarcoma (HOS) CD4 cells. Phylogenetic analysis of V3 loop sequences showed that ES1158.1 and ES1159.1 isolates were closely related to the ANT70 strain, whereas MD.1 isolate clustered with the MVP-5180 strain in the same branch. Interestingly, all viruses appeared to be more closely related to the MVP-5180 strain when the protease gene was analyzed, although accessible sequences of this region are very limited.

Amino Acid Sequence↗
PubMed1997

Mycosis fungoides and Sezary syndrome are not associated with HTLV-I infection: an international study.

Association between mycosis fungoides (MF), its leukaemic variant Sezary syndrome (SS) and the human T-cell lymphotropic virus type-I (HTLV-I) has been controversial, with the reported incidence of infection varying between 0% and nearly 100%. We studied 127 patients (85 MF, 28 SS, five Sezary cell leukaemia, four lymphomatoid papulosis, and five unspecified cutaneous T-cell lymphomas (CTCL)) originating from Europe (France, Spain, U.K., Portugal) or from U.S.A. (California) for the presence of HTLV-I infection markers. HTLV-I and -II serology were performed on 78 patients using standard immunological methods. Reverse transcriptase (RT) assay was also performed in 26 cases using an RT-PCR-based method of high sensitivity. Molecular analyses were performed on 215 DNA samples (121 from fresh PBMCs, 26 from PBMCs after short-term culture and 68 from skin lesions) by PCR amplification using HTLV-I and -II gag, pol, env, pX and LTR specific primers. Immunological tests were negative except for two sera which were indeterminate. PCR with all HTLV-I and -II primer pairs showed negative results in all 215 samples investigated. No RT activity was detected in short-term PBMC cultures of any of the 26 cases studied. The results of this large study from five different countries clearly indicate that MF and SS are not associated with HTLV-I infection.

Blotting, Western↗
PubMed1997

[Frequency and characteristics of patients treated with zidovudine and absence of progression of HIV infection].

BACKGROUND: the efficacy of zidovudine (ZDV) is lost in many treated individuals after a few weeks or months of monotherapy. The development of drug resistance seems to explain this adverse event. However, some individuals seem to persistently benefit clinically and immunologically from ongoing ZDV monotherapy. The degree and causes of this phenomenon remain unclear. PATIENTS AND METHODS: we studied 280 HIV-infected patients who have been receiving ZDV monotherapy for more than 18 months (mean 28 +/- 7 months), and whom has a CD4+ count between 200 and 500 x 10(6)/l at baseline. We classified them into two groups: Non-progressors with ZDV (NP-ZDV), subjects with an increase or a reduction < 15% in the CD4+ count; and Progressors with ZDV (P-ZDV), subjects showing a decline in the CD4 count > 15%. Epidemiological, immunological and virological features of each group were compared. RESULTS: the prevalence of NP-ZDV in this population was 15.7% (44/280). Age, gender, and risk behaviour were not significantly different in NP-ZDV and P-ZDV. Although the CD4/CD8 ratio, as well as the CD45R0/CD45RA ratio into the CD4+ subpopulation, were higher in NP-ZDV than in P-ZDV, the values did not achieve statistical significance. Virological studies were performed on 36 (81.8%) NP-ZDV and 55 (23.3%) P-ZDV. Mean HIV-RNA titer was higher in P-ZDV than in NP-ZDV (8.4 x 10(4) vs. 1.5 x 10(3) copies/ml; p < 0.01). Virus isolation from circulating mononuclear cells was made more frequently in P-ZDV than in NP-ZDV (90.9% vs. 81.5%), although it did not achieve statistical significance. The syncitium-inducing (SI) phenotype was detected in more than a quarter (27.3%) of P-ZDV but was absent in NP-ZDV (p < 0.01). The prevalence of RT mutations at codon 215 was much lower in NP-ZDV than in P-ZDV, and it showed a strong statistical significance (13.9% vs. 74.5%; p < 0.01). CONCLUSIONS: prolonged (> 2 years) lack of immunological and clinical progression can be observed in 15% of HIV-infected persons with mild immunosuppression, undertaking ZDV monotherapy. This effect seems to be associated with a characteristic virological profile, in which a low viral load, the absence of SI phenotype, and a lack of development of ZDV-resistance are the most relevant features.

Adult↗
PubMed1996

Nucleotide sequence and restriction fragment-length polymorphism analysis of human T-cell lymphotropic virus type II (HTLV-II) in southern Europe: evidence for the HTLV-IIa and HTLV-IIb subtypes.

Human T-cell lymphotropic virus type II (HTLV-II) has been subtyped into two major groups, IIa and IIb, according to molecular studies involving env gene sequencing. Subsequently, this retrovirus was further subclassified by examining the long terminal repeat (LTR), the most divergent genomic region. Sequence analysis and restriction fragment-length polymorphism (RFLP) applied to the LTR region identified either four or five groups within the IIa subtype (depending on the restriction enzyme sets used) and six within the IIb subtype. In this study, we analyzed the LTR sequences of 29 samples obtained from HTLV-II-infected individuals living in Spain and Italy, which included 24 injecting drug users (IDUs), three blood donors, and two subjects at risk for HIV/HTLV infection. Sequence analysis and phylogenetic analysis of 720 base pairs of the LTR performed in 10 Spanish samples showed that all of these samples belonged to IIb subtype, with a divergence of 7.5% and 1.66% compared with MoT (IIa) and NRA/G12 (IIb) isolates, respectively. RFLP analysis demonstrated the presence of the IIb 4-subtype restriction pattern in 26 samples, a IIb5-subtype pattern in one Italian IDU, and a IIa0-subtype pattern in two Italian samples (blood donors), according to W.M. Switzer's nomenclature. This is the first report of the presence of IIb5 in Southern Europe and IIa0 among Italian blood donors. RFLP correlated with nucleotide sequence and phylogenetic data obtained in this study, demonstrating the ability of the RFLP method to predict the phylogroup of HTLV-II-infected samples.

Base Sequence↗