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Biomedical subjects

M I Gutierrez

Publications and source records attributed to M I Gutierrez.

At least 19 recordsLinked to original sources
PubMed2006

The US National Violent Death Reporting System: domestic and international lessons for violence injury surveillance.

OBJECTIVES: This article reviews and comments on the development, strengths and limitations of the US National Violent Death Reporting System (NVDRS) from a variety of domestic and international perspectives. METHODS: The authors were provided preliminary copies of the manuscripts in this special edition and examined them to understand and put in context the elements and uses of the NVDRS so far. Their comments are based on their reading and interpretation of these papers plus their own combined experience in injury and public health surveillance from four different countries: the US, Colombia, Australia, and South Africa. RESULTS: The NVDRS is bigger than the sum of its parts because it links existing data from multiple sources. Its adoption of modern relational database technologies offers advantages over traditional injury surveillance databases and creates new opportunities for understanding, collaboration, and partnerships. Challenges include overcoming resource limitations so that it can become a truly national system, measuring and improving its sensitivity and comparability, and the need to examine mortality in context with serious non-fatal violent events. CONCLUSIONS: The NVDRS is an important work in progress for the US. Each country should examine its own needs, traditions, resources, and existing infrastructure when deciding what kind of violence surveillance system to develop. However, collaboration in developing common definitions and classifications provides an important foundation for international comparisons.

Databases, Factual↗
PubMed2004

Paucity of TEL-AML 1 translocation, by multiplex RT-PCR, in B-lineage acute lymphoblastic leukemia (ALL) in Indian patients.

A total of 69 patients of B lineage ALL, 35 children (32 males, 3 females) and 34 young adults (27 males, 7 females) were studied by multiplex RT-PCR to determine the relative frequency of t(9;22), t(12;21), t(1;19), and t(4;11,). Translocation (9;22) was seen in 1/35 (2.8%) and t(1;19) in 2/35 (5.7%) children. None of the children showed t(12;21) and t(4;11) translocations. In young adults, t(9;22) and t(1;19) were seen in 5/34 (14.7%) and 2/34 (5.8%) patients, respectively. None of the latter showed t(12;21) or t(4;11) translocations. Thus, there appears to be a significant under representation of the fusion transcripts for TEL-AML, a good prognostic marker, in this study, unlike in the West, where it is seen in 35% of children with ALL. This, together with the generally increased leukemic burden seen in Indian patients, may explain in part, the poor treatment outcome reported.

Adolescent↗
PubMed2003

Concurrent methylation of multiple genes in childhood ALL: Correlation with phenotype and molecular subgroup.

Multiple genes have been shown to be independently hypermethylated in lymphoid malignancies. We report here on the extent of concurrent methylation of E-cadherin, Dap-kinase, O(6)MGMT, p73, p16, p15 and p14 in 129 pediatric ALL cases. While most of these genes demonstrated methylation in a proportion of cases, O(6)MGMT, p16 and p14 were infrequently methylated (11, 7 and 3%, respectively). Methylation of at least one gene was found in the vast majority (83%) of cases. To determine the extent and concordance of methylation we calculated a methylation index (MI=number of methylated genes/number of studied genes) for each sample. The average MI was 0.28, corresponding to 2/7 methylated genes. MI was correlated with standard prognostic factors, including immunophenotype, age, sex, WBC and presence of specific translocations (TEL-AML1, BCR-ABL, E2A-PBX1 or MLL-AF4). We determined that children >/=10 years old and children presenting with high WBC (>/=50 x 10(9)/l) both associated with a higher MI (P<0.01 and <0.05, respectively). T-ALLs demonstrated a lower MI (median=0.17) than precursor B ALLs (median=0.28). Among the different molecular subgroups, MLL-ALLs had the highest MI (mean=0.35), while ALLs carrying the t(1;19) had the lowest MI (mean=0.07). The most common epigenetic lesion in childhood ALL was methylation of E-cadherin (72%) independent of the molecular subtype or other clinicopathological factors.

Adolescent↗
PubMed2001

Clinical significance of the arthroscopic drive-through sign in shoulder surgery.

PURPOSE: During arthroscopy of the shoulder, the ability to pass the arthroscope easily between the humeral head and the glenoid at the level of the anterior band of the inferior glenohumeral ligament is considered a positive drive-through sign. The drive-through sign has been considered diagnostic of shoulder instability and has been associated with shoulder laxity and with SLAP lesions. The goal of this study was to examine the prevalence of the drive-through sign in patients undergoing shoulder arthroscopy and to determine its relationship to shoulder instability, shoulder laxity, and to SLAP lesions. TYPE OF STUDY: Case series. METHODS: We prospectively studied 339 patients undergoing arthroscopy of the shoulder for a variety of diagnosis from 1992 to 1998. The drive-through sign was performed with the patients in a lateral decubitus position and under general anesthesia. The drive-through sign was correlated with preoperative physical findings, intraoperative laxity testing, and with intra-articular pathology at the time of arthroscopy. RESULTS: The arthroscopic evaluation showed that drive-through sign was positive in 234 (69%) shoulders. For the diagnosis of instability, the drive-through sign had a sensitivity of 92%, a specificity of 37. 6%, a positive predictive value of 29.9%, a negative predictive value of 94.2%, and an overall accuracy of 49%. There was an association between the drive-through sign and increasing shoulder laxity, but not with SLAP lesions. CONCLUSIONS: This study shows that a positive drive-through sign is not specific for shoulder instability but is associated with shoulder laxity. This arthroscopic sign should be incorporated with other factors when considering the diagnosis of instability.

Adolescent↗
PubMed2000

E2F family members are differentially regulated by reversible acetylation.

The six members of the E2F family of transcription factors play a key role in the control of cell cycle progression by regulating the expression of genes involved in DNA replication and cell proliferation. E2F-1, -2, and -3 belong to a structural and functional subfamily distinct from those of the other E2F family members. Here we report that E2F-1, -2, and -3, but not E2F-4, -5, and -6, associate with and are acetylated by p300 and cAMP-response element-binding protein acetyltransferases. Acetylation occurs at three conserved lysine residues located at the N-terminal boundary of their DNA binding domains. Acetylation of E2F-1 in vitro and in vivo markedly increases its binding affinity for a consensus E2F DNA-binding site, which is paralleled by enhanced transactivation of an E2F-responsive promoter. Acetylation of E2F-1 can be reversed by histone deacetylase-1, indicating that reversible acetylation is a mechanism for regulation also of non-histone proteins.

Acetylation↗
PubMed2000

Identification of specific molecular structures of human immunodeficiency virus type 1 Tat relevant for its biological effects on vascular endothelial cells.

Human immunodeficiency virus type 1 (HIV-1) Tat transactivates viral genes and is released by infected cells, acting as a soluble mediator. In endothelial cells (EC), it activates a proangiogenic program by activating vascular endothelial growth factor receptor type 2 (VEGFR-2) and integrins. A structure-activity relationship study was performed by functional analysis of Tat substitution and deletion variants to define the Tat determinants necessary for EC activation. Variants were made (i) in the basic and (ii) in the cysteine-rich domains and (iii) in the C-terminal region containing the RGD sequence required for integrin recognition. Our results led to the following conclusions. (i) Besides a high-affinity binding site corresponding to VEGFR-2, EC express low-affinity binding sites. (ii) The basic and the cysteine-rich variants bind only to the low-affinity binding sites and do not promote tyrosine phosphorylation of VEGFR-2. Furthermore, they have a reduced ability to activate EC in vitro, and they lack angiogenic activity. (iii) Mutants with mutations in the C-terminal region are partially defective for in vitro biological activities and in vivo angiogenesis, but they activate VEGFR-2 as Tat wild type. In conclusion, regions encoded by the first exon of tat are necessary and sufficient for activation of VEGFR-2. However, the C-terminal region, most probably through RGD-mediated integrin engagement, is indispensable for full activation of an in vitro and in vivo angiogenic program.

Base Sequence↗
PubMed2000

Parenting and physical punishment: primary care interventions in Latin America.

Physical punishment is a form of intrafamilial violence associated with short- and long-term adverse mental health outcomes. Despite these possible consequences, it is among the most common forms of violent interpersonal behavior. For many children it begins within the first year of life. The goal of this study was to determine the feasibility of involving public sector primary health care providers to inform parents about alternatives to physical punishment. The study used a qualitative design utilizing focus groups and survey questionnaires with parents and providers at six clinic sites chosen to be representative of public sector practice settings in Costa Rica and in metropolitan Santiago, Chile. The data were collected during 1998 and 1999. In the focus groups and surveys the parents voiced a range of opinions about physical punishment. Most acknowledged its common use but listed it among their least preferred means of discipline. Frequency of its use correlated positively with the parents' belief in its effectiveness and inversely with their satisfaction with their children's behavior. Some parents wanted to learn more about discipline; others wanted help with life stresses they felt led them to use physical punishment. Parents reported they chose other family members more frequently as a source of parenting information than they did health care providers. Some parents saw providers as too rushed and not knowledgeable enough to give good advice. Providers, in turn, felt ill equipped to handle parents' questions, but many of the health professionals expressed interest in more training. Parents and providers agreed that problems of time, space, and resources were barriers to talking about child discipline in the clinics. Many parents and providers would welcome a primary-care-based program on physical punishment. Such a program would need to be customized to accommodate local differences in parent and provider attitudes and in clinic organization. Health care professionals need more training in child discipline and in the skills required to interact with parents on issues relating to child behavior.

Adolescent↗
PubMed2000

Association of Burkitt's lymphoma with the Epstein-Barr virus in two developing countries.

The clinical presentation of Burkitt's lymphoma (BL) and it's association with the Epstein-Barr virus (EBV) varies in different geographic areas, BL in developing countries being "intermediate" between the sporadic and endemic types, both in it's clinical presentation and it's association with EBV, which varies from 25-80%. In this study we have analysed the clinical features, EBV association, subtype and prevalence of the deleted variant of the Latent Membrane Protein-1 (LMP-1) of EBV in forty-two cases from two developing countries- India (n = 25) and Argentina (n = 17). In both countries the abdomen was the site most commonly involved while jaw involvement was rare. EBV was detected by in-situ hybridization using the EBER-1 RNA probe. 47% of cases from Argentina and 80% of cases from India were EBER positive. EBV typing using EBNA-3C primers showed a predominance of Type A in both countries (India-13/16 and Argentina-(7/8)). The 30bp deletion of the LMP-1 gene was detected in all evaluated cases from Argentina while the wild type of the gene was seen in all the evaluable Indian cases. Our study highlights the similarities and differences in the clinical presentation and EBV association of BL in two developing countries and also indicates that the subtype of EBV and prevalence of the LMP-1 deletion may reflect the predominant subtype in a particular population.

Adolescent↗
PubMed1999

Human immunodeficiency virus type 1 tat protein activates transcription factor NF-kappaB through the cellular interferon-inducible, double-stranded RNA-dependent protein kinase, PKR.

The transactivator protein of human immunodeficiency virus type 1 (HIV-1) (Tat) is a powerful activator of nuclear factor-kappaB (NF-kappaB), acting through degradation of the inhibitor IkappaB-alpha (F. Demarchi, F. d'Adda di Fagagna, A. Falaschi, and M. Giacca, J. Virol. 70:4427-4437, 1996). Here, we show that this activity of Tat requires the function of the cellular interferon-inducible protein kinase PKR. Tat-mediated NF-kappaB activation and transcriptional induction of the HIV-1 long terminal repeat were impaired in murine cells in which the PKR gene was knocked out. Both functions were restored by cotransfection of Tat with the cDNA for PKR. Expression of a dominant-negative mutant of PKR specifically reduced the levels of Tat transactivation in different human cell types. Activation of NF-kappaB by Tat required integrity of the basic domain of Tat; previous studies have indicated that this domain is necessary for specific Tat-PKR interaction.

3T3 Cells↗
PubMed1998

HIV-1 tat transactivator recruits p300 and CREB-binding protein histone acetyltransferases to the viral promoter.

In cells infected with HIV type 1 (HIV-1), the integrated viral promoter is present in a chromatin-bound conformation and is transcriptionally silent in the absence of stimulation. The HIV-1 Tat protein binds to a stem-loop structure at the 5' end of viral mRNA and relieves this inhibition by inducing a remodeling of the nucleosome arrangement downstream of the transcription-initiation site. Here we show that Tat performs this activity by recruiting to the viral long terminal repeat (LTR) the transcriptional coactivator p300 and the closely related CREB-binding protein (CBP), having histone acetyltransferase (HAT) activity. Tat associates with HAT activity in human nuclear extracts and binds to p300 and CBP both in vitro and in vivo. Integrity of the basic domain of Tat is essential for this interaction. By a quantitative chromatin immunoprecipitation assay we show that the delivery of recombinant Tat induces the association of p300 and CBP with the chromosomally integrated LTR promoter. Expression of human p300 in both human and rodent cells increases the levels of Tat transactivation of the integrated LTR. These results reinforce the evidence that p300 and CBP have a pivotal function at both cellular and viral promoters and demonstrate that they also can be recruited by an RNA-targeted activator. Additionally, these findings have important implications for the understanding of the mechanisms of HIV-1 latency and reactivation.

CREB-Binding Protein↗
PubMed1998

In vitro selection of HIV-1 TAR variants by the Tat protein.

Starting from a pool of 10(13) RNA sequences, we isolated a number of TAR RNA variants after nine rounds of selection by binding to recombinant Tat in vitro (SELEX procedure). Sequence analysis of part of the selected molecular species indicated that two TAR variants (clones A and B) were, respectively, represented five and four times. These two groups of sequences constituted approximately 25% of the total number of analyzed clones (9/34). As far as the primary and presumptive secondary structures of the wild-type TAR are concerned, the selected A and B variants showed an almost complete sequence conservation of the Tat-binding domain, but the configuration of this nucleotide region differed within the secondary structure. Despite this difference, as verified by gel retardation and filter binding assays, both the A and B variants bound Tat in vitro with an affinity that was very close to that of the wild-type TAR. Conversely, neither variant sustained Tat-mediated trans-activation in vivo when they replaced the wild-type TAR inside the long terminal repeat of HIV_1. Taken together, our results suggest that these TAR variants have lost the ability to bind cell factor(s) in vivo and may therefore represent useful decoys for the inhibition of HIV-1 replication.

Base Sequence↗
PubMed1997

Role of the p53 tumor suppressor gene in the tumorigenicity of Burkitt's lymphoma cells.

Burkitt's lymphoma (BL) cell lines carry a translocated c-myc gene and, in 60-80% of cases, exhibit mutations in the p53 tumor suppressor gene. We examined the potential role of the p53 gene in BL tumorigenicity using an in vitro assay that measures p53-dependent cell cycle arrest in the G1 phase of the cell cycle and an in vivo athymic murine model that detects differences in the tumorigenicity of BL cell lines. A highly significant inverse correlation was found between the ability of BL cells to arrest in G1 after irradiation and their tumorigenicity in athymic mice, consistent with the notion that loss of p53 function is associated with increased tumorigenicity. Inactivation of wild-type (wt) p53 function by expression of the human papillomavirus E6 protein in the AG876V BL cell line, which carries both wt and mutant p53 proteins, rendered the cell line significantly more tumorigenic in athymic mice. Transfection of the wt p53 gene into the p53 mutant and highly tumorigenic BL-41 cell line caused it to acquire wt p53 function and rendered it less tumorigenic in mice. In addition to confirming a role for the loss of p53 function in tumor progression, the data demonstrate that wt p53 protein can reduce BL tumorigenicity in vivo.

Animals↗
PubMed1995

Molecular and functional interactions of transcription factor USF with the long terminal repeat of human immunodeficiency virus type 1.

The human transcription factor USF, purified from HeLa cells, and its recombinant 43-kDa component bind to the long terminal repeat (LTR) of human immunodeficiency virus type 1. The proteins footprint over nucleotides from position -173 to -157 upstream of the transcription start site, generating strong DNAse I hypersensitivity sites at the 3' sides on both strands. As detected by methylation protection studies, the factor forms symmetric contacts with the guanines of the palindromic CACGTG core of the recognized sequence. Its binding ability is abolished by the mutation of this core sequence and is strongly reduced by the cytosine methylation of the central CpG dinucleotide. Upon binding, both recombinant and purified USFs bend the LTR DNA template. The role of USF in the control of transcription initiation from the LTR was tested by in vitro transcription assays. Upon addition of the protein, transcription from constructs containing an intact binding site is increased, while the responsiveness in constructs with a mutated sequence is abolished. Furthermore, the addition of a decoy plasmid which contains multiple repeats of the target sequence results in downregulation of transcription from the LTR. These results suggest that USF is a positive regulator of LTR-mediated transcriptional activation.

Base Sequence↗
PubMed1993

Replicative viral DNA in Epstein-Barr virus associated Burkitt's lymphoma biopsies.

Epstein-Barr virus (EBV) is linked to a spectrum of human diseases including epithelial and lymphoid malignancies in which it exists predominantly in a latent state. EBV is capable of establishing replicative infection at oropharyngeal and genital sites. Replicative EBV infection also occurs in oral hairy leukoplakia, in EBV associated lymphoproliferative disorders, and to a minor degree in nasopharyngeal carcinomas. Recent evidence also suggests that EBV replication, also, may be associated with AIDS related lymphomas and Hodgkin's disease. However it is widely believed that virus in circulating B-lymphocytes and in B-cell malignancies is stringently latent. We now show that by Southern blot analysis we can detect replicative forms of virion DNA in 14.5% (8 of 55) of EBV-positive Burkitt's lymphoma biopsies. This may be the explanation for the elevation of the titres of lytic cycle EBV antigens that is associated with presentation and relapse of EBV associated Burkitt's lymphoma.

Biopsy↗
PubMed1992

Infrequent p53 mutation in mouse tumors with deregulated myc.

An invariant genetic lesion in mouse plasmacytomas is deregulated expression of c-myc as a consequence of chromosomal translocation. However, retroviral and transgenic studies suggest that additional genetic lesions may contribute to the genesis of plasmacytomas. The p53 tumor suppressor gene is a likely contributor to this genetic lesion, since there is a high incidence of p53 mutation in Burkitt's lymphomas and B-ALL (L3), both of which contain translocations involving c-myc analogous to those in plasmacytomas. In addition, p53 has been shown to be a transcriptional modulator of c-myc expression. In a survey of 27 mouse plasmacytomas by single-strand conformation polymorphism, we identified a single mutation (3.7% incidence), suggesting that p53 lesions are not frequent contributors to plasmacytomagenesis. A similar study of macrophage-monocyte tumors generated by a c-myc-containing retrovirus also indicates a lack of p53 involvement in deregulated c-myc expression. These results suggest that the specific maturation stage of transformed B-lymphocytes, independent of c-myc deregulation, may be the critical factor which determines the involvement of mutant p53.

Amino Acid Sequence↗
PubMed1992

A human binding site for transcription factor USF/MLTF mimics the negative regulatory element of human immunodeficiency virus type 1.

Transcriptional regulation of the proviral form of the human immunodeficiency virus type 1 (HIV-1) is exerted by its 5' long terminal repeat (LTR), which contains recognition sites for several cell factors. By gel retardation and DNase I footprinting experiments we have identified a binding site for a human nuclear protein between nucleotides -152 to -174 upstream of transcription start site, in a region previously recognized as a negative regulator of transcription (negative regulatory element, NRE). The recognized sequence contains the dyad symmetry element CACGTG, which represents a binding motif, very conserved through evolution, present in a putative human DNA replication origin (pB48), in the upstream element of the major late promoter (MLP-UE) of adenovirus, and, as transcriptional element, upstream of many eukaryotic genes. Common binding activities exist in human nuclear extracts for pB48, MLP-UE and the HIV-1 LTR; at least three protein species recognize the LTR sequence, of 44 (corresponding to transcription factor USF/MLTF), 70, and 110 kDa, respectively. Chloramphenicol acetyltransferase assays suggest that the USF/MLTF binding site located in the HIV-1 LTR acts as a negative regulator of transcription, and that it contributes to the overall negative function exerted by the NRE. An oligonucleotide corresponding to another characterized human USF/MLTF binding site can functionally replace part of the activity of the NRE. This negative function is exerted both in presence or absence of tat transactivation, in different cell lines, and after PMA stimulation.

Adenoviruses, Human↗