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Biomedical subjects

A Villa

Publications and source records attributed to A Villa.

At least 109 records · Page 6Linked to original sources
PubMed1999

[Milk fluoridation program in Codegua, Chile: evaluation after 3 years].

A study was done in 1994 to determine the effectiveness of the fluoridated dairy products that the Chilean National Program for Supplementary Feeding had been distributing to reduce the high prevalence of children's dental caries in rural areas of that country. For the study, the prevalence of caries was assessed in two rural communities of the Sixth Region of Chile. Children in the study community of Codegua had received fluoridated dairy products, while children in the control community of La Punta had received nonfluoridated dairy products. Three years after the program began in Codegua, the community showed a significant improvement in the indices of prevalence of caries. Over that time period, the prevalence of caries among children 3 to 6 years old declined between 40% and 60%. Among children 3 years old, the proportion of them without a history of caries increased by 74%, from 40.7% to 70.8%. Among 4-year-olds, that proportion rose by 71%, from 33.3% to 56.9%. Similar to results obtained elsewhere with programs to fluoridate drinking water, the outcomes in Codegua were achieved without any other steps by the National Program for Supplementary Feeding, such as motivational campaigns for mothers or educational efforts to encourage consumption of the program's food products.

Age Factors↗
PubMed1999

[Osteoporosis in Mexican postmenopausal women. Magnitude of the problem. Multicenter study].

Incidencia of osteoporosis induced fractures increases with age; risk increases exponentially as bone mass decreases. Women are prone to osteoporosis 2 to 3 times more than men, due to lower "peak" bone mass and the accelerated loss that occurs after the menopause. The prevalence of osteoporosis in with Caucasian postmenopausal women varies from 16 to 30% depending upon the number of sites measured (lumbar spine/hip and/or forearm). The aim of this study was to estimate the prevalence of osteopenia and osteoporosis in pre and postmenopausal Mexican women in relation to men, and to that reported in Caucasia women. The study involved 4,821 apparently healthy subjects (without known risk factors for osteoporosis), 4,467 females and 354 males from 11 different centers of Mexican Republic, 20 to 90 years old, using DXA bone densitometry of lumbar spine and hip. Prevalence of osteoporosis in women is twice that in men (P < 0.001), and it increases with age, particularly after the menopause (P < 0.0001). Our study found a prevalence of osteoporosis of the lumbar spine and/or hip in apparently healthy postmenopausal Mexican women over 50 years of age of 16%, increasing to 20% in those women with or without risk factors who attended voluntarily or by suggestion of their physician to be studied. The prevalence values obtained seem to be lower than those reported for Caucasian women, 30%. We found a prevalence of osteoporosis of 16% and of osteopenia of 57% in women 50 years of age and older. We also found a higher prevalence of osteoporosis in women of the south east part of the county.

Female↗
PubMed1999

Prenatal diagnosis of JAK3 deficient SCID.

The JAK3 gene, encoding a tyrosine kinase functionally coupled to cytokine receptors which share the common gamma chain, has been identified as the defective gene for autosomal recessive severe combined immunodeficiency (SCID). Thus, specific mutational diagnosis has become possible. We screened all exons with a combined single strand conformational polymorphism and hetero-duplex formation assay followed by sequence analysis to identify specific mutations in two families. This assay was used on chorionic villus sampling derived DNA in two fetuses from two unrelated families, where we found mutations in both parents. We were able to exclude the mutations in both fetuses by the 12th week of gestation. The described method for first-trimester prenatal diagnosis of autosomal recessive T-B+SCID provides a valid tool to aid in genetic counselling and possibly prenatal therapy in this disease.

Alleles↗
PubMed1998

Thymocyte contact or monoclonal antibody-mediated clustering of 3beta1 or 6beta4 integrins activate interleukin-6 (IL-6) transcription factors (NF-kappaB and NF-IL6) and IL-6 production in human thymic epithelial cells.

T-cell precursors develop within the thymus in contact with multiple supportive elements, among which thymic epithelial cells (TEC) are known to exert a dominant role in their homing, survival, and functional differentiation. All these functions are supported by cell-cell contacts and cytokine release. Signaling events triggered in lymphoid cells by adhesion to TEC are well characterized, but little is known about the opposite phenomenon. To address this issue, we derived cultures of TEC from human normal thymus. TEC monolayers were cocultured with thymocytes and immunostained with monoclonal antibodies (MoAbs) to integrin (2, 3, 4, and 6) and beta (beta1 and beta4) chains. Optical and confocal analysis showed that integrins were polarized on TEC at discrete surface locations: 6beta4 lined the basal surface of TEC monolayers, whereas 3beta1 was found mostly at TEC-TEC contacts; it is noteworthy that both 3beta1 and 6beta4 became highly enriched also at the boundaries with adherent thymocytes. Functional studies performed with MoAbs anti-beta1 and -beta4 integrins showed that beta1, and, to a much lower extent, beta4 heterodimers are involved in the TEC-thymocyte adhesion. Thymocyte contact or MoAb-mediated ligation of 3, 6, beta1, and beta4 integrins was investigated as a potential inducer of intracellular signaling in TEC. Thymocyte adhesion or cross-linking of MoAbs bound to integrins clustered at the TEC/thymocyte contact sites led to activation of interleukin-6 (IL-6) gene transcription factors, namely NF-IL6 serine phosphorylation and NF-kappaB nuclear targeting, as well as to increased IL-6 secretion. We propose that integrin clustering occurring during TEC-thymocyte contacts modulates in TEC the gene expression of a cytokine involved in thymocyte growth and functional differentiation.

Antibodies, Monoclonal↗
PubMed1998

Thyroid hormone negatively regulates the transcriptional activity of the beta-amyloid precursor protein gene.

The expression of the beta-amyloid precursor protein (APP), which plays a key role in the development of Alzheimer's disease, is regulated by a variety of cellular mediators in a cell-dependent manner. In the present study, we present evidence that thyroid hormones negatively regulate the expression of the APP gene in neuroblastoma cells. Transient transfection studies using plasmids that contain progressive deletions of the 5' region of the gene demonstrate that triiodothyronine (T3), the more active form of the thyroid hormones, represses APP promoter activity by a mechanism that requires binding of the nuclear T3 receptor (TR) to a specific sequence located in the first exon. The unliganded receptor increases promoter activity, and T3 reverses that activity to basal levels. The repressive effect of T3 does not exhibit TR isoform specificity, and it is equally mediated by TRalpha and TRbeta. Gel mobility shift assays using in vitro synthesized nuclear receptors and nuclear extracts led to the identification of a negative thyroid hormone response element, at nucleotide position +80/+96, that preferentially binds heterodimers of TR with the retinoid X receptor. Insertion of sequences containing this element confers negative regulation by T3 to a heterologous TK promoter, thus indicating the functionality of the element.

Amyloid beta-Protein Precursor↗
PubMed1998

Affinity chromatography purification of mitochondrial inner membrane proteins with calcium transport activity.

Immobilized calcium affinity chromatography was used to obtain a preparation enriched in calcium transporters from Triton X-100 extracts of rat liver mitochondria inner membranes (PPCT). The PPCT were reconstituted into preformed asolectin liposomes which contained 120 mM KCl as internal high K+ medium. 45Ca2+ uptake into proteoliposomes was studied under conditions favoring electrophoretic uptake, and H+i/45Ca2+o or Na+i/45Ca2+o exchange, to test for the presence of the three calcium transport modes present in mitochondria. 45Ca2+ uptake in liposomes was studied in parallel. Na+i/45Ca2+o exchange activity was not detectable. H+i/45Ca2+o exchange activity measured in the presence of a pH gradient (acid inside) obtained after suspension in low K medium in the presence of nigericin, was 100-200 nmoles 45Ca2+ per mg protein in 30 s. 45Ca2+ uptake in voltage-dependent assays (a K+ diffusion membrane potential induced by valinomycin in the presence of methylamine) was not electrophoretic since it was stimulated by carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) and probably due to secondary Ca2+/H+ countertransport. H+i/45Ca2+o uptake showed a saturable component at around 80 microM Ca and was coupled to an increase in internal pH in pyranine-loaded PPCT proteoliposomes. 45Ca2+ uptake in PPCT proteoliposomes could also be driven by a pH gradient obtained by raising external pH in high K+ medium. The results are consistent with the presence of a functional nH+/Ca2+ antiporter. Polyclonal antibodies raised against the PPCT were able to immunoprecipitate the H+/45Ca2+ uptake activity and recognized two major bands in the PPCT with molecular masses of about 66 kDa and 55 kDa. This is the first report of a partial purified protein(s) which may represent the H+/Ca2+ exchanger of the inner mitochondrial membrane, and represents an important step towards its identification.

Animals↗
PubMed1998

Junctional adhesion molecule, a novel member of the immunoglobulin superfamily that distributes at intercellular junctions and modulates monocyte transmigration.

Tight junctions are the most apical components of endothelial and epithelial intercellular cleft. In the endothelium these structures play an important role in the control of paracellular permeability to circulating cells and solutes. The only known integral membrane protein localized at sites of membrane-membrane interaction of tight junctions is occludin, which is linked inside the cells to a complex network of cytoskeletal and signaling proteins. We report here the identification of a novel protein (junctional adhesion molecule [JAM]) that is selectively concentrated at intercellular junctions of endothelial and epithelial cells of different origins. Confocal and immunoelectron microscopy shows that JAM codistributes with tight junction components at the apical region of the intercellular cleft. A cDNA clone encoding JAM defines a novel immunoglobulin gene superfamily member that consists of two V-type Ig domains. An mAb directed to JAM (BV11) was found to inhibit spontaneous and chemokine-induced monocyte transmigration through an endothelial cell monolayer in vitro. Systemic treatment of mice with BV11 mAb blocked monocyte infiltration upon chemokine administration in subcutaneous air pouches. Thus, JAM is a new component of endothelial and epithelial junctions that play a role in regulating monocyte transmigration.

Amino Acid Sequence↗
PubMed1998

DNA ligase I is recruited to sites of DNA replication by an interaction with proliferating cell nuclear antigen: identification of a common targeting mechanism for the assembly of replication factories.

In mammalian cells, DNA replication occurs at discrete nuclear sites termed replication factories. Here we demonstrate that DNA ligase I and the large subunit of replication factor C (RF-C p140) have a homologous sequence of approximately 20 amino acids at their N-termini that functions as a replication factory targeting sequence (RFTS). This motif consists of two boxes: box 1 contains the sequence IxxFF whereas box 2 is rich in positively charged residues. N-terminal fragments of DNA ligase I and the RF-C large subunit that contain the RFTS both interact with proliferating cell nuclear antigen (PCNA) in vitro. Moreover, the RFTS of DNA ligase I and of the RF-C large subunit is necessary and sufficient for the interaction with PCNA. Both subnuclear targeting and PCNA binding by the DNA ligase I RFTS are abolished by replacement of the adjacent phenylalanine residues within box 1. Since sequences similar to the RFTS/PCNA-binding motif have been identified in other DNA replication enzymes and in p21(CIP1/WAF1), we propose that, in addition to functioning as a DNA polymerase processivity factor, PCNA plays a central role in the recruitment and stable association of DNA replication proteins at replication factories.

Amino Acid Sequence↗
PubMed1998

Partial V(D)J recombination activity leads to Omenn syndrome.

Genomic rearrangement of the antigen receptor loci is initiated by the two lymphoid-specific proteins Rag-1 and Rag-2. Null mutations in either of the two proteins abrogate initiation of V(D)J recombination and cause severe combined immunodeficiency with complete absence of mature B and T lymphocytes. We report here that patients with Omenn syndrome, a severe immunodeficiency characterized by the presence of activated, anergic, oligoclonal T cells, hypereosinophilia, and high IgE levels, bear missense mutations in either the Rag-1 or Rag-2 genes that result in partial activity of the two proteins. Two of the amino acid substitutions map within the Rag-1 homeodomain and decrease DNA binding activity, while three others lower the efficiency of Rag-1/Rag-2 interaction. These findings provide evidence to indicate that the immunodeficiency manifested in patients with Omenn syndrome arises from mutations that decrease the efficiency of V(D)J recombination.

Amino Acid Sequence↗
PubMed1998

Development of autologous, oligoclonal, poorly functioning T lymphocytes in a patient with autosomal recessive severe combined immunodeficiency caused by defects of the Jak3 tyrosine kinase.

Defects of the common gamma chain subunit of the cytokine receptors (gamma c) or of Jak3, a tyrosine kinase required for gamma c signal transduction, result in T-B+ severe combined immunodeficiency (SCID). However, atypical cases, characterized by progressive development of T lymphocytes, have been also reported. We describe a child with SCID caused by Jak3 gene defects, which strongly but not completely affect Jak3 protein expression and function, who developed a substantial number (> 3,000/microL) of autologous CD3+CD4+ T cells. These cells showed a primed/activated phenotype (CD45R0+ Fas+ HLA-DR+ CD62L(lo)), defective secretion of T-helper 1 and T-helper 2 cytokines, reduced proliferation to mitogens, and a high in vitro susceptibility to spontaneous (caused by downregulation of bcl-2 expression) as well as activation-induced cell death. A restricted T-cell receptor repertoire was observed, with oligoclonal expansion within each of the dominant segments. These features resemble those observed in gamma c-/y and in Jak3-/- mice, in which a population of activated, anergic T cells (predominantly CD4+) also develops with age. These results suggest that residual Jak3 expression and function or other Jak3-independent signals may also permit the generation of CD4+ T cells that undergo in vivo clonal expansion in humans; however, these mechanisms do not allow development of CD8+ T cells, nor do they fully restore the functional properties of CD4+ T lymphocytes.

Cell Death↗
PubMed1998

The clinical predictivity of biomarkers of stage III-IV epithelial ovarian cancer in a prospective randomized treatment protocol.

BACKGROUND: The aim of this study was to define the clinical relevance of functional biomarkers, prospectively assessed in a randomized clinical protocol, in patients with Stage III-IV epithelial ovarian cancer. The protocol compared cisplatin with polychemotherapy that included cisplatin and cyclophosphamide. METHODS: In a subset of 168 patients with invasive epithelial ovarian cancer cell proliferation was determined by the 3H-thymidine labeling index, DNA ploidy was assessed by flow cytometry, and the expression of p53, bcl-2, and glutathione S-transferase-pi (GST-pi) was evaluated by immunohistochemistry using the antibodies PAb1801, anti-bcl-2, and GST-pi, respectively. RESULTS: Cell proliferation, DNA ploidy, and the expression of p53, bcl-2, and GST-pi were generally unrelated to one another and unrelated to clinicopathologic features, except for an association between DNA ploidy and the rate of cell proliferation. All biologic variables except bcl-2 were slightly related to tumor grade. DNA ploidy emerged as a predictor of clinical complete response and 3-year overall survival, regardless of treatment type or residual disease. Conversely, except for a favorable outcome for patients with tumors not expressing bcl-2 who were treated with cisplatin, no definitive patterns of predictivity for short term or long term clinical outcomes were observed for the other biomarkers studied. CONCLUSIONS: DNA ploidy appears to be the most clinically relevant biomarker for epithelial ovarian cancer. More information is needed to understand the role of the other markers studied in this tumor type.

Aged↗
PubMed1998

Establishment and characterization of a new mammary adenocarcinoma cell line derived from MMTV neu transgenic mice.

A new murine cell line, named MG1361, was established from mammary adenocarcinomas arising in a MMTV-neu transgenic mouse lineage where breast tumors develop in 100% of females, due to the overexpression of the activated rat neu oncogene in the mammary gland. The MG1361 cell line shows an epithelial-like morphology, has a poor plating efficiency, low clonogenic capacity, and a doubling time of 23.8 hours. Karyotype and flow cytometry analysis revealed a hypotetraploid number of chromosomes, whereas cell cycle analysis showed 31.2% of cells to be in the G1 phase, 21.4% in S and 47.4% in G2 + M. This cell line maintains a high level of neu expression in vitro. The MG1361 cell line was tumorigenic when inoculated in immunodeficient (nude) mice and the derived tumors showed the same histological features as the primary tumors from which they were isolated. MG1361 cells were positive for specific ER and PgR binding which was competed by tamoxifen, making this cell line useful for the evaluation of endocrine therapy. Moreover, they were sensitive to etoposide treatment, suggesting that they could be a model for the study of chemotherapy-induced apoptosis. As the tumors arising in MMTV-neu transgenic mice have many features in common with human mammary adenocarcinomas (Sacco et al., Gene Therapy 1995; 2: 493-497), this cell line can be utilized to perform basic studies on the role of the neu oncogene in the maintenance of the transformed phenotype, and to test novel protocols of therapeutic strategies.

Adenocarcinoma↗
PubMed1998

Survival and prognostic factors of early ovarian cancer.

Survival and prognostic factors were analysed in 150 patients with histologically confirmed epithelial ovarian cancer stage IA-IIA. The relapse-free and overall survival rates were, respectively, 81% and 88% after 3 and 74% and 84% after 5 years. The analysis of various prognostic factors indicates as the main factor the grade differentiation of the tumour.

Adult↗
PubMed1998

In vitro and in vivo antisense-mediated growth inhibition of a mammary adenocarcinoma from MMTV-neu transgenic mice.

Oncogene-bearing transgenic mice develop various kinds of tumors depending on both the regulatory sequences and the specific oncogene used. These mice not only help to clarify the pathogenetic pathways leading to tumor formation, but can also be useful as models to test novel therapeutic strategies, including gene therapy. We have previously reported the establishment of an MMTV-neu (ErbB-2) transgenic mouse lineage, in which 100% of females develop breast tumors with many features similar to their human counterparts; these tumors are due to the over-expression of the activated rat neu oncogene in the mammary gland. From one such mouse we established a cell line of mammary adenocarcinoma named MG1361. We report here that the growth of this cell line can be inhibited in vitro and in vivo by transfection of a plasmid vector carrying an antisense anti-neu construct. This inhibitory effect is specific, as it is related to the expression of the antisense transgene (determined by RT-PCR), and to a reduction in neu mRNA and protein, as determined by Northern and Western blot analyses. Moreover, inoculation of cells carrying the antisense or the control vector in nude mice demonstrated that the morphological and biochemical effects elicited by the antisense construct resulted in a significantly slower rate of in vivo growth of tumor xenografts. Finally, significant mammary tumor growth inhibition was obtained after liposome-mediated direct inoculation of the same antisense vector in tumors spontaneously arising in MMTV-neu mice. Taken together, these findings suggest that targeting neu expression by an integrated large anti-neu antisense segment affects the in vivo growth of these tumors.

Adenocarcinoma↗
PubMed1998

Molecular and biochemical characterization of JAK3 deficiency in a patient with severe combined immunodeficiency over 20 years after bone marrow transplantation: implications for treatment.

Severe combined immunodeficiency (SCID) comprises a heterogenous group of disorders that are fatal unless treated by bone marrow transplantation (BMT). The most common form of SCID (T-B+ SCID) is due to mutations of either the common gamma chain (gammac) or of gammac-coupled JAK3 kinase. We report an unusual JAK3 defect in a female who was successfully treated > 20 years ago with a BMT using her HLA-identical father as the donor. Persistence of genetically and biochemically defective autologous B cells, associated with reconstitution of cellular and humoral immunity, suggests that integrity of the gammac-JAK3 signalling pathway is not strictly required for immunoglobulin production.

B-Lymphocytes↗