PubMed Health⌕ Search

Biomedical subjects

A Holguín

Publications and source records attributed to A Holguín.

At least 19 recordsLinked to original sources
PubMed2006

Skin gene therapy for acquired and inherited disorders.

The rapid advances associated with the Human Genome Project combined with the development of proteomics technology set the bases to face the challenge of human gene therapy. Different strategies must be evaluated based on the genetic defect to be corrected. Therefore, the re-expression of the normal counterpart should be sufficient to reverse phenotype in single-gene inherited disorders. A growing number of candidate diseases are being evaluated since the ADA deficiency was selected for the first approved human gene therapy trial (Blaese et al., 1995). To cite some of them: sickle cell anemia, hemophilia, inherited immune deficiencies, hyper-cholesterolemia and cystic fibrosis. The approach does not seem to be so straightforward when a polygenic disorder is going to be treated. Many human traits like diabetes, hypertension, inflammatory diseases and cancer, appear to be due to the combined action of several genes and environment. For instance, several wizard gene therapy strategies have recently been proposed for cancer treatment, including the stimulation of the immune system of the patient (Xue et al., 2005), the targeting of particular signalling pathways to selectively kill cancer cells (Westphal and Melchner, 2002) and the modulation of the interactions with the stroma and the vasculature (Liotta, 2001; Liotta and Kohn, 2001).

Animals↗
PubMed2005

HIV-1 subtypes in Spain: a retrospective analysis from 1995 to 2003.

OBJECTIVE: To perform a retrospective analysis of all HIV-1 non-B variants circulating in Spain from 1995 to 2003 and extend their virological characterization. METHODS: Samples from a total of 396 HIV-infected subjects with epidemiological suspicion of being infected with non-B clades were analysed during the study period. Subtyping was carried out on the protease (PR), reverse transcriptase (RT) and envelope (env) genes. RESULTS: PR sequences belonging to non-B subtypes were recognized in 43.2% of cases (23 A, 13C, 6D, 3F, 118 G, 3H, 4 J and 1 U). Subtype G and AG recombinants were the most frequent variants (69%), and were found most often in subjects from West and Central Africa. Up to 70% of pol (PR, RT) sequences belonging to subtype G harboured env sequences belonging to clade A (55%), B (13.8%) or K (3.4%). Nearly half were mosaic GA viruses, and a few were CRF 14 BG viruses. Up to 14 new recombinant viruses, which could not be assigned to previously described circulating recombinant forms (CRFs), were found. CONCLUSIONS: There is great diversity in the HIV-1 variants and recombinant viruses circulating in Spain. Non-B sequences may be underestimated if only the env region is examined in phylogenetic analyses. Drug resistance testing provides the advantage of pol subtyping, and its additional use for this purpose should be encouraged.

CD4 Lymphocyte Count↗
PubMed2003

Performance of drug resistance assays in testing HIV-1 non-B subtypes.

Antiretroviral susceptibility analyses were performed in plasma samples collected from 32 HIV-1 non-B-infected individuals, most of whom had received antiretroviral drugs. Reverse transcriptase (RT) and protease gene sequences were obtained, and 15 anti-HIV drugs were tested in a recombinant virus phenotypic assay. Phenotypic results were obtained in 25 (78.1%) samples, while genotypic data were recorded in 19 (59.4%). In seven samples (21.9%), neither genotypic nor phenotypic results were obtained. Ten of 13 samples with plasma HIV RNA below 2000 copies/mL did not yield genotypic results. Resistance assays work accurately when testing HIV-1 non-B subtypes. However, as for subtype B variants, a low viral load is the most important factor limiting the application of these tests.

Anti-HIV Agents↗
PubMed2003

Human immunodeficiency virus type 1 recombinant B/G subtypes circulating in Coimbra, Portugal.

An increasing prevalence of HIV-1 non-B variants is being noticed in several European regions, particularly in countries such as Portugal, which have closer contacts with African endemic areas, where multiple HIV subtypes cocirculate. HIV-1 subtyping by phylogenetic analyses of reverse transcriptase, protease and env (C2-V3) genomic regions was carried out in plasma collected from 18 HIV-1-infected subjects living in Coimbra, Portugal, and suspected to be infected with non-B variants. Three (16.7%) subjects carried recombinant B/G viruses (BV3/BRT/Gpro; GV3/URT/Bpro; AV3/GRT/Bpro), whereas all the remaining individuals were infected with HIV-1 subtype B. This is the first report of recombinant B/G subtypes in Portugal.

Adult↗
PubMed2003

[Thomas' shunt for hemodialysis: dysfunction and its percutaneous treatment].

PURPOSE: To assess the usefulness of percutaneous treatment of abnormalities of the venous tree in extending the survival of external Thomas shunts (TS). MATERIALS AND METHODS: Twelve cases of TS were included in a hemodialysis access fistula dysfunction monitoring program and were followed for up to 48 months. The abnormalities found were treated by percutaneous transluminal angioplasty (PTA) or thrombolysis and PTA. Survival curves and the Kaplan-Meier method were used to calculate the likelihood of primary patency (P1), secondary patency (P2), and overall patency (OP). RESULTS: A total of 61 interventions were performed during the period of follow-up. On 12 occasions the fistula was thrombosed; in the rest, increased venous pressure to 150 mmHg or higher was detected during dialysis. Fistulography was performed after washing the thrombosed fistulas with urokinase, and revealed one or more of the following angiographic signs: 1) a short reduction of more than 50% in lumen caliber in the femoral vein adjacent to the anastomosis, present in 52% of the cases (fig. 1); 2) imaging a "jet" of contrast material at the site of entry of the shunt into the femoral vein (fig. 2), present in 22% of the cases; and 3) a filling defect or "flap" at the same site, owing to hyperplastic tissue or piece of thrombus adhering to the intima, present in 34% of the cases (figs. 3-5). This last-mentioned finding ordinarily gave rise to a "valve" effect, whereby injection into the venous branch was feasible but aspiration from the venous branch was difficult or impossible. PTA was carried out and attained anatomical and functional success in 100% of cases. PI was 58%, 33%, 8%, and 0% at 6, 12, 24, and 36 months, respectively; P2 was 100%, 75%, 58%, and 25%; respectively, at those same times. The comparison of the PI and P2 curves was statistically significant; p < 0.001 (table 1). OP was 83%, 66%, 50% and 41% at 12, 24, 36 and 48 months. The comparison of the PI surgical and OP curves was statistically significant; p < 0.01 (table II). CONCLUSIONS: Percutaneous treatment of TS dysfunction was proved to be effective in maintaining long-term patency. This type of fistula affords an alternative to tunneled central venous catheters.

Adult↗
PubMed2002

Prevalence of different HIV-1 subtypes in an urban clinic in Madrid.

The introduction of non-B HIV-1 variants into Western Europe and North America is of great concern since diagnostic tools and drugs are mainly optimised for targeting HIV-1 subtype B viruses. Madrid is an endemic area for HIV, and either the final destination or transient location for many immigrants from HIV-1 non-B endemic areas (mainly from Africa and South America). From a total of 902 HIV seropositive individuals examined since June 1999, only 27 (3%) were found to be infected with non-B HIV variants. However, up to 71.4% of African immigrants carried non-B viruses. Therefore, HIV subtyping should be requested from all HIV infected African immigrants before considering viral load testing and recommending antiretroviral therapy.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Prevalence of human immunodeficiency virus type 1 (HIV-1) non-B subtypes in foreigners living in Madrid, Spain, and comparison of the performances of the AMPLICOR HIV-1 MONITOR version 1.0 and the new automated version 1.5.

Plasma specimens collected in 1999 from 32 human immunodeficiency virus type 1 (HIV-1)-infected foreigners living in Madrid, Spain, were examined for the presence of non-B subtypes. Furthermore, plasma viremia was quantified using two different AMPLICOR HIV-1 MONITOR tests, version 1.0 and the new upgraded and automated version 1.5 (COBAS). Most patients came from Africa, where they most likely had acquired HIV-1 infection through sexual contact. HIV-1 genetic subtyping was based on the phylogenetic analysis of the protease gene. Twenty-two subtype B, six subtype G, two subtype C, one subtype A, and one D subtype infection were found. Overall, non-B subtypes represented 31.25% of the study population. Irrespective of the HIV-1 variant, viral load values above the detection limit (200 HIV RNA copies/ml) increased from 56.2 to 71.9% for results obtained using MONITOR version 1.0 and COBAS, respectively. Moreover, significant differences in viral load values (>0.5 logs) were recognized in up to 37.5% of samples. In summary, COBAS seemed to be more reliable for testing plasma viral load in HIV-infected immigrants living in Spain, one third of whom carried non-B subtypes.

Adult↗
PubMed2000

Protease gene analysis of HIV type 1 non-B subtypes in Spain.

The protease gene of human immunodeficiency virus type 1 (HIV-1) clinical isolates found in 15 immigrants (most of African origin) living in Spain was examined. Phylogenetic analyses were performed, taking as reference a panel of 26 HIV protease gene sequences deposited with GenBank. All specimens belonged to four distinct HIV-1 non-B subtypes: C (three cases), F (one), G (nine), and H (two). Five patients harboring subtype G strains were further classified within the IbNg recombinant clade. A high degree of genetic polymorphism at the protease gene was seen in all subtypes. Moreover, changes at positions associated with drug resistance were seen in subtype G viruses carried by patients who had not been exposed to protease inhibitors. Plasma viremia was lower than expected for some samples, according to the clinical features and the CD4+ cell count, suggesting that viral load titers were underestimated by all three commercially available techniques. This work represents the first genetic characterization of subtypes C, F, G, and H in Spain.

Adult↗
PubMed2000

Recombinant human immunodeficiency viruses type 1 circulating in Spain.

The protease, reverse transcriptase (RT), and envelope (env) genes of human immunodeficiency virus type 1 (HIV-1) clinical isolates from 13 immigrants (mainly of African origin) living in Spain were examined. Phylogenetic analyses were performed, taking as reference a panel of 25 HIV-1 sequences representing various subtypes. A discrepant topology was recognized in comparing the protease, RT, and/or env phylogenetic trees in 10 isolates, in which sequences clustering in 2 or 3 different HIV-1 subtypes were found. In eight of these strains, the discrepant region was env with respect to concordant pol genes. Five of nine patients harboring subtype G sequences at the protease and RT genes showed discrepant env sequences, being subtype A (three) or B (two). In addition, one recombinant H/A strain, one recombinant H/B isolate, and a triple recombinant, A/D/C, variant were found. This work represents the first phylogenetic characterization of HIV-1 recombinant clinical isolates in Spain.

Adult↗
PubMed2000

Emergence of drug resistance mutations in human immunodeficiency virus type 2-infected subjects undergoing antiretroviral therapy.

The reverse transcriptase (RT) and protease genes from 12 human immunodeficiency virus type 2 (HIV-2)-infected individuals who had been exposed to antiretroviral drugs for longer than 6 months were examined for the presence of mutations which could be involved in drug resistance. Four individuals carried virus genotypes with amino acid substitutions potentially associated with resistance to nucleoside analogues: two at codon 70 (K-->R) and two at codon 184 (M-->V). Moreover, the latter two patients harbored a codon Q151M mutation which is associated to multidrug resistance in HIV-1, and one of these subjects carried some of the typically linked mutations at codons 65 and 69. With regard to the protease inhibitors, substitutions associated with resistance to protease inhibitors at codon 46 were observed in all individuals. Moreover, minor resistance mutations, as well as new ones of unknown meaning, were often seen in the protease gene. In conclusion, amino acid changes in the HIV-2 RT and protease genes which could be associated with drug resistance seem to occur at positions identical to those for HIV-1.

Adolescent↗
PubMed2000

Human immunodeficiency virus type 2 (HIV-2) in Portugal: clinical spectrum, circulating subtypes, virus isolation, and plasma viral load.

The human immunodeficiency virus type 2 (HIV-2) is responsible for 4. 5% of AIDS cases in Portugal. Six HIV-2 subtypes have been described so far, subtype A being proposed as more pathogenic than the rest. The relationship between the clinical status and levels of both cellular and plasma HIV-2 viraemia is not well known, nor their modifications under antiretroviral therapy. Thirty-two consecutive HIV-2 infected persons (17 men, 15 women) attending two different hospitals in Lisbon in 1997 were enrolled prospectively in the study. All but 4 individuals most likely acquired the infection through heterosexual contact. More than half of the study population was of African origin, mainly from Guinea-Bissau. Eleven (34.4%) patients had developed clinical manifestations included within the B or C groups of the CDC classification system for HIV infection, with the rest being asymptomatic. Half of the population was undergoing antiretroviral treatment at the time of the study. HIV-2 subtypes were investigated using a new Nef-based restriction fragment length polymorphism (RFLP) method that allows differentiation of the main two variants, A and B. Plasma viral load was quantified using a new quantitative competitive reverse transcriptase polymerase chain reaction (QcRT-PCR) procedure as well as the Amp-RT assay. Virus isolation was attempted from peripheral blood mononuclear cells. All but one person carried HIV-2 subtype A. Plasma viraemia examined by QcRT-PCR was measurable in 15 (50%) of 30 subjects, yielding in all instances values below 20,000 HIV-2 RNA copies per ml. Plasma RT activity could be detected in only 10 (33%) of 30 subjects, a rate much lower than that seen in HIV-1 infection. Virus was isolated from 16 (53.3%) of 30 patients. A significant correlation was found between CD4+ counts, clinical status, rate of virus isolation, and plasma viral load by both QcRT-PCR and Amp-RT. In conclusion, HIV-2 subtype A is the predominant variant circulating in Portugal among both natives and immigrants. A lower cellular and plasma viral load with respect to HIV-1 was seen in persons without immunosuppression, from whom the rate of virus recovery was extremely low.

Female↗
PubMed1999

Multiple drug resistance genotype causing failure of antiretroviral treatment in an HIV-infected patient heavily exposed to nucleoside analogues.

A 37-year-old homosexual man began antiretroviral combination therapy with didanosine (ddI), lamivudine (3TC) and indinavir (IDV) after being exposed previously to zidovudine (ZDV), ddI and 3TC in different sequential regimens. The patient's viral load did not fall below a detectable level despite his adherence to drug therapy, which was considered optimal. Stavudine (d4T) was prescribed in the third month of treatment instead of ddI without any evident improvement in the treatment response. A point mutation nested PCR assay showed that the patient carried a virus with a codon Q151M mutation, which confers multiple drug resistance to nucleoside analogues. Genetic sequence analysis showed that, despite none of the classically associated mutations to Q151M being present at the beginning of treatment, continuous genetic evolution under selective drug pressure allowed the virus to accumulate mutations at codons 62, 74 and 116 over time. As expected, the CD4+ cell count declined during the study period, and the viral load remained detectable.

Adult↗
PubMed1999

Comparison of three different commercial methods for measuring plasma viraemia in patients infected with non-B HIV-1 subtypes.

In order to determine whether commercial assays presently in use for the quantification of plasma human immunodeficiency virus type 1 (HIV-1) RNA levels detect different genetic viral subtypes with the same reliability, a panel of 38 samples corresponding to 22 HIV-1-infected patients, representing non-B subtypes A-F, was examined. One to three plasma samples belonging to each individual were tested by the second-generation HIV-1 branched DNA (bDNA) assay (Chiron, Spain), the Nuclisens assay (Organon-Teknika, Spain), the Amplicor Monitor reverse transcriptase polymerase chain reaction assay (Roche, Spain), and the Ultradirect Monitor (Roche) using primers specifically designed to amplify non-B HIV-1 subtypes. Each of the different methods for measuring viral load showed a distinct sensitivity for non-B HIV-1 subtypes. Values higher than the assay detection limit were obtained in 22 (57.9%), 33 (86.8%), and 37 (93.3%) samples using the bDNA, Nuclisens, and Monitor assays, respectively. Significantly different values (>0.5 logs) were found in 55.3%, 81.6%, and 71.1% of specimens comparing results provided by bDNA and Nuclisens, bDNA and Monitor, and Nuclisens and Monitor, respectively. Quantitative values provided by the Ultradirect Monitor test using non-B primers were particularly discordant with the other tests. Overall, 44.7% of samples yielded higher viral load values with this assay than with the regular Monitor assay, reflecting its enhanced sensitivity for non-B subtypes; however, the reproducibility of this test was low. These results support the recommendation of always using the same assay when monitoring plasma viraemia.

HIV Infections↗
PubMed1999

Human immunodeficiency virus type 2 infection in Spain. The HIV-2 Spanish Study Group.

The first cases of human immunodeficiency virus type 2 (HIV-2) infection in Spain were identified in 1988, in 3 African immigrants living in Barcelona. Since then, up to December 1998, 92 individuals with HIV-2 infection have been reported in Spain. Most are adult men, infected through heterosexual contacts, originating from West African countries, and currently living in the largest urban Spanish cities. Fifteen individuals have developed AIDS, meanwhile the rest remain asymptomatic. For 22 subjects, HIV-2 subtyping was performed on proviral DNA, 16 being infected with subtype A (8 Spanish born and 8 African immigrants) and the remaining with subtype B (two Spanish born and 4 originating from Equatorial Guinea). Coinfection with HIV-1 was demonstrated in 9 individuals. In conclusion, HIV-2 is currently circulating in Spain with a low prevalence and without evidence for increase over time.

Adult↗
PubMed1999

Human immunodeficiency viruses type 1 subtypes circulating in Sspain.

Genetic subtypes of Human immunodeficiency viruses type 1 (HIV-1) were investigated in 101 HIV-1-infected individuals living in Spain from 1993 to 1998. Samples selected randomly from the HIV clinic population included 29 Spanish native born subjects (28.7%) and 72 foreigners (71.3%). Proviral DNA extracted from peripheral blood mononuclear cells (PBMCs) or viral RNA isolated from plasma was amplified, and endonuclease restriction analysis was carried out on polymerase chain reaction (PCR) products. Restriction fragment length polymorphism (RFLP) analysis on the HIV-1 protease region enabled the characterisation of the different HIV genotypes infecting these individuals. Overall, 38 subjects (37.6%) carried non-B subtypes (A in 26, C in 2, D in 1, E in 2, and F in 7), 31 (81. 6%) of them being immigrants. Direct sequence analysis of PCR products and/or a specific serological assay confirmed the data obtained by RFLP in most individuals tested. In conclusion, different HIV-1 subtypes are circulating currently in Spain, with non-B HIV-1 subtypes being confined mostly to immigrants.

Adult↗