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Biomedical subjects

M Salcedo

Publications and source records attributed to M Salcedo.

At least 37 records · Page 2Linked to original sources
PubMed2001

The evidence for an etiological relationship between oral contraceptive use and dysplastic change in cervical tissue.

A case-control study of 112 patients with cervical intraepithelial neoplasia (CIN) and 131 control subjects was conducted. Estradiol receptor levels were determined in the total (cytosolic-nucleosolic) fraction of the neoplastic cervical specimens taken during the late proliferative phase of their cycle from 58 premenopausal patients who had been oral contraceptive (OC) users for at least 2 years and from 54 premenopausal women who had not been OC users. All specimens contained variable amount of estradiol receptor (from 7.6 to 53.0 fmol estradiol/mg protein and 7.2 to 29.3 fmol estradiol/mg protein in patients who were OC users and non-users, respectively). A significant correlation was found between estradiol receptor concentration and histological grading in both groups, likewise higher levels of estradiol receptor were observed in the low-grade CIN group tissue from patients who were OC users (p < 0.05). At the same time 17 beta-estradiol and progesterone levels were also determined in the serum of all women who had not used an OC for at least 12 months. The mean +/- SD estradiol serum levels in non-users of OC with CIN (0.189 +/- 0.08 ng/ml, follicular phase) were greater than the mean +/- SD (1.163 +/- 0.33 ng/ml, luteal phase) progesterone serum concentration. Serum estradiol levels were significantly higher (p < 0.05) in OC users, whereas progesterone levels were not (p > 0.05). OC users had an increased risk (odds ratio = 1.31, 95% CI 1.0-2.3) of cervical neoplasia.

Adult↗
PubMed2001

Relationship between estradiol 16 alpha-hydroxylation and human papillomavirus infection in cervical cell transformation.

The ovarian steroid hormone estradiol and its metabolite estrone were examined in 45 normal women and 127 premenopausal women with precancerous cervical lesions. Interviews, colposcopy and cervical scrapings were performed. The mean +/- SD values for estradiol and estrone were 0.07 +/- 0.08 ng/ml and 0.06 +/- 0.02 ng/ml, respectively in normal subjects. Corresponding data in patients with cervical intraepithelial neoplasia alone or in association with human papillomavirus (HPV) infection were 0.074 +/- 0.03 ng/ml and 0.076 +/- 0.03 ng/ml or 0.080 +/- 0.03 ng/ml and 0.148 +/- 0.02 ng/ml, respectively, which revealed a significantly greater extent of estrogenic action in the latter population (p < 0.05). We considered that the presence of HPV infection probably increased 16 alpha-hydroxylation of estradiol, providing a possible link between the viral and hormonal elements, possibly having a bearing on the etiology of the disease.

Adolescent↗
PubMed2000

In vivo neutrophil dysfunction in cirrhotic patients with advanced liver disease.

Bacterial infections are frequent, life-threatening complications in cirrhotic patients. This study investigated in vivo neutrophil migration and phagocytic activity in cirrhotic patients with advanced liver disease, in liver transplant recipients, and in healthy volunteers, by use of the skin window technique. Complement receptor type III (CR3) expression was also measured in blood and elicited neutrophils. Neutrophil migration to skin windows and neutrophil in vivo phagocytosis of heat-killed Escherichia coli were significantly decreased in cirrhotic patients compared with healthy controls. Neutrophil migration and phagocytosis were decreased in cirrhotic patients with previous episodes of bacterial infection compared with noninfected patients. Expression of CR3 in circulating neutrophils was significantly higher in cirrhotic patients, whereas it was significantly reduced in elicited neutrophils of cirrhotic patients with previous bacterial infection. These data suggest that deficient neutrophil recruitment to the infection site and impaired phagocytic activity may contribute to bacterial infections in cirrhotic patients with advanced liver disease.

Aged↗
PubMed2000

Nonstochastic coexpression of activation receptors on murine natural killer cells.

Murine natural killer cells (NK) express lectin-like activation and inhibitory receptors, including the CD94/NKG2 family of receptors that bind Qa-1, and the Ly-49 family that recognizes major histocompatibility complex class I molecules. Here, we demonstrate that cross-linking of NK cells with a new specific anti-Ly-49H mAb induced NK cell cytotoxicity and cytokine production. Ly-49H is expressed on a subset of NK cells and can be coexpressed with Ly-49 inhibitory receptors. However, unlike Ly-49 inhibitory receptors, Ly-49H is not detectable on naive splenic CD3(+) T cells, indicating that Ly-49H may be an NK cell-specific activation receptor. In further contrast to the stochastically expressed Ly-49 inhibitory receptors, Ly-49H is preferentially expressed with the Ly-49D activation receptor, and expression of both Ly-49H and Ly-49D is augmented on NK cells that lack receptors for Qa-1 tetramers. On developing splenic NK1.1(+) cells, Ly-49D and Ly-49H are expressed later than the inhibitory receptors. These results directly demonstrate that Ly-49H activates primary NK cells, and suggest that expression of Ly-49 activation receptors by NK cells may be specifically regulated on NK cell subsets. The simultaneous expression of multiple activation receptors by individual NK cells contrasts with that of T cell antigen receptors and is relevant to the role of NK cells in innate immunity.

Animals↗
PubMed2000

Role of Qa-1(b)-binding receptors in the specificity of developing NK cells.

NK cells acquire the ability to recognize MHC class I molecules during development. Studies with Qa-1(b) tetramers (Qa-1 tetramers) showed that nearly all NK1.1(+) cells from newborn C57BL/6 mice express Qa-1-binding receptors. Cytotoxic activity of these cells is fully inhibited by Qa-1 ligands on target cells. In contrast, neither receptors for H-2K(b) nor H-2D(b) were observed on NK1.1(+) cells from newborn mice. After birth, frequencies of Qa-1 tetramer(+)/ NK1.1(+) cells gradually decrease as the number of Ly49(+) /NK1.1(+) cells increases. Cell transfer studies showed that Qa-1 tetramer(+) cells from newborn mice do not lose expression of Qa-1 receptors, but that they further acquire expression of Ly49 molecules. Acquisition of Qa-1-binding receptors appears largely independent of host MHC class I molecules, as observed in studies using beta2-microglobulin-deficient (beta2m(-/-)) mice as well as K(b)/ D(b-/-) and K(b)/D(b)/beta2m(-/-) mice. The present results suggest that Qa-1-binding receptors play an important role in the specificity of developing NK cells, and suggest that these cells rely mainly on inhibitory receptors specific for non-classical MHC class I molecules to maintain self tolerance during the first weeks of life.

Adoptive Transfer↗
PubMed2000

Visualization of inhibitory Ly49 receptor specificity with soluble major histocompatibility complex class I tetramers.

Murine natural killer (NK) cells are inhibited from killing their targets by the interaction between inhibitory, C-type lectin like Ly49 receptors and major histocompatibility complex (MHC) class I molecules. The receptors have overlapping specificity, and it has been difficult to analyze specific aspects of the interaction between different Ly49 receptors and their respective ligands. We have addressed this problem using tetramers of bacterially expressed, non-glycosylated, MHC class I molecules refolded with different peptides. Our results indicate that this technology is useful for analysis of Ly49 receptor specificity as well as for monitoring of NK cell subsets, with the following major conclusions emerging from this study: (1) tetramers of H-2D(d) bound the Ly49A receptor; the MHC associated glycan, previously suggested to be involved in recognition by this receptor, is thus not required for Ly49A receptor binding; (2) in support and extension of a recent report indicating peptide selectivity in the recognition of H-2K(b) by Ly49C(+) cells, H-2K(b) tetramer binding to Ly49C receptors was strongly influenced by the peptide presented by the MHC class I molecule; (3) tetramer binding allowed visualization of interactions that have not previously been detected in functional studies, such as the recognition of H-2D(b) by Ly49A and Ly49C.

Animals↗
PubMed2000

Modulation of ICAM-1 tissue expression in patients with liver transplantation (LT) and acute rejection (AR) after glucocorticoid treatment.

Acute rejection (AR) is a frequent complication following liver transplantation (LT). ICAM-1 may be involved in its pathogenesis. High doses of glucocorticoids are the standard treatment in these patients. The aim of this study was to describe corticoid effects on ICAM-1 tissue expression in liver biopsies of patients with LT and AR. The study included liver biopsies performed before and after treatment in 12 patients with LT and proven AR. In 10 patients AR was reversible and in 2, was steroid resistant. For immunohistochemistry, an indirect immunoperoxidase technique was used. Each histology section was semiquantitatively evaluated as follows: 0: < 10% staining, 1: 10-25%, 2: 25-50%, 3: > 50%. The control group comprised nine patients with LT and normal liver biopsies. In pre-treatment liver biopsy samples, ICAM-1 was markedly expressed on sinusoidal cells (2.41 +/- 0.66), and there was also expression on periportal (0.66 +/- 0.65) and perivenular hepatocytes (0.83 +/- 0.57). By contrast, in the liver tissue from the control group, sinusoidal ICAM-1 reactivity was significantly lower (0.88 +/- 0.33; P < 0.05), and hepatocytes showed no reliable ICAM-1 expression. After steroid treatment the intensity of ICAM-1 decreased significantly in sinusoids (1.5 +/- 0.67; P < 0.05) and in perivenular hepatocytes (0.25 +/- 0.86; P < 0.05). Additionally, we also observed a decreased ICAM-1 reactivity in portal hepatocytes (0.25 +/- 0.62), but these differences did not reach statistical significance. Remarkably, after treatment, hepatocytes did not show ICAM-1 reactivity in resolved AR, but in corticoid-resistant patients AR did not change or increase. In conclusion, in patients with LT and AR, ICAM-1 was expressed in hepatocytes and with more intensity in sinusoid cells. Additionally, a down-regulation of the ICAM-1 tissue expression after corticoid treatment may exist, although in corticoid-resistant AR no modulation on ICAM-1 tissue expression was observed.

Acute Disease↗
PubMed2000

Human papilloma virus status and chromosomal imbalances in primary cervical carcinomas and tumour cell lines.

Human papilloma virus (HPV) infection is the crucial step in the initiation of cervical carcinomas. In addition, HPV18 has been implicated in tumour progression and adverse clinical outcome. We determined the HPV types in 12 primary cervical carcinomas and 12 cell lines and compared the findings with the comparative genetic hybridisation (CGH) pattern of chromosomal alterations. The most frequent alteration was the deletion at 3p14 followed by the loss of 2q34-q36 along with 3q gain. High risk HPV types were detected in all samples except one primary tumour. In contrast to the normal distribution, HPV18 was present in 75% of cases including all cell lines. The cell lines carried a higher number of genetic alterations and a different CGH pattern for several chromosomes than the primary tumours, despite microdissection. Purely HPV18 positive cases indicated a high incidence of imbalances at specific loci with peaks of the histogram coinciding with known HPV integration sites. The study suggests that HPV infection is associated with a recurrent pattern of chromosomal changes in cervical carcinomas and that the development and progression of these alterations is triggered by integration into the host genome.

Carcinoma, Squamous Cell↗
PubMed2000

Hyperlipidemic nephropathy induced by adriamycin in ovariectomized rats: role of free radicals and effect of 17-beta-estradiol administration.

The present study in rats evaluates the effects of the ovariectomy (OVX) with and without the simultaneous administration of 17beta-estradiol (17betaE(2)) on oxidative stress and hyperlipidemic nephropathy induced by a single high dose of adriamycin (AD). OVX enhances oxidative stress and worsens nephropathy induced by AD. These changes are prevented by simultaneous administration of 17betaE(2). OVX alone induced oxidative stress and hyperlipidemia without biochemical evidence of renal dysfunction. Our results revealed that ovarian hormones, especially estrogens, have a protective effect against oxidative stress and nephropathy induced by AD. Since the reactive oxygen species plays a role in the pathogenesis of renal lesion, it is important to emphasize that estrogens and their hydroxylated compounds function as biological antioxidants.

Animals↗
PubMed2000

Simplified method to generate large quantities of dendritic cells suitable for clinical applications.

The present study describes the optimization of an in vitro culture method for generating large amounts of dendritic cells (DC) in serum-free conditions from leukapheresis containing a mixed population of peripheral blood mononuclear cells (PBMC) which are cultured in the presence of GM-CSF and IL-13. Initial comparisons between the generation of DC from bulk and monocyte-enriched leukapheresis products showed that the presence of lymphocytes during the culture favors the differentiation of monocytes into DC. DC yields obtained from mixed mononuclear cell cultures were between 38 and 54% higher than yields obtained from monocyte-enriched cultures. Both types of cultures resulted in the generation of DC with an immature phenotype (CD83- and high phagocytic activity), which have been previously shown to be good stimulators for T cell responses. DC yields of bulk cultures in serum-free conditions were significantly higher than those obtained in the presence of 2% human serum. The cytokines of the supernatants of serum-free cultures comprised a significant content of pro-inflammatory cytokines such as IL-1, IL-12 and TNF-alpha. Maturation of DC generated by this method can be induced by treatment with double-stranded RNA, LPS or TNF-alpha, resulting in enhanced surface expression of CD80, CD86, CD40, CD83 and MHC molecules on the DC. The methodology described here offers the possibility for generating large amounts of clinical grade DC from bulk leukapheresis products, thus avoiding DC precursor purification steps, and thereby minimizing the risks of contamination. This culture process may be applied to cell-based therapeutic approaches for the treatment of cancer or chronic viral infections.

Cell Communication↗
PubMed1999

IFN-gamma production and cytotoxicity of IL-2-activated murine NK cells are differentially regulated by MHC class I molecules.

Activation of NK cells by target cells leads to cytotoxicity as well as production of various cytokines including IFN-gamma. MHC class I molecules on target cells regulate NK cytotoxicity. However, little is known about the regulation of IFN-gamma production by NK cells. We examined the production of IFN-gamma in individual murine NK cells stimulated with tumor cell lines by flow cytometric analysis of intracellular IFN-gamma. Among several tumor lines tested, the rat basophilic leukemia line RBL-1 induced particularly high level of IFN-gamma production in IL-2-activated NK cells, whereas other lines, including the prototypic NK target YAC-1, induced very low or no IFN-gamma production. Transfection of murine classical MHC class I molecules into RBL-1 cells substantially inhibited IFN-gamma production. This inhibition of IFN-gamma production by MHC class I was independent of Ly-49 or CD94/NKG2A expression on NK cells. These results indicate that some target cells directly stimulate IL-2-activated NK cells and induce IFN-gamma production, but the requirements for the induction of IFN-gamma production seem different from those for NK cytotoxicity. Furthermore, similar to NK cytotoxicity, induction of IFN-gamma production is inhibited by MHC class I on stimulating cells. However, the MHC class I-specific receptors inhibiting IFN-gamma production are different from those for NK cytotoxicity.

Animals↗
PubMed1999

Stochastic acquisition of Qa1 receptors during the development of fetal NK cells in vitro accounts in part but not in whole for the ability of these cells to distinguish between class I-sufficient and class I-deficient targets.

Fetal mouse NK cells are grossly deficient in the expression of Ly49 molecules yet show a limited ability to distinguish between wild-type and MHC class I-deficient target cells. In this paper we report that during their development in vitro from immature thymic progenitors, a proportion of C57BL/6 fetal NK cells acquires receptors for a soluble form of the nonclassical class I molecule Qa1b associated with the Qdm peptide, but not for soluble forms of the classical class I molecules Kb and Db. The acquisition of these Qa1 receptors occurs in a stochastic manner that is strictly controlled by cytokines, and in particular is strongly inhibited by IL-4. All fetal NK clones tested, including those that lack detectable Qa1 receptors, express mRNA for CD94 and for both inhibitory and noninhibitory members of the NKG2 family. Fetal NK cells lacking receptors for Qa1 (and also for classical class I molecules) cannot distinguish between wild-type and class I-deficient blasts but, surprisingly, distinguish efficiently between certain wild-type and class I-deficient tumor cells. A variant line that lacks several members of the NKG2 family kills both types of tumor cell equally well, suggesting the existence of NKG2-containing inhibitory receptors that recognize as yet undefined nonclassical class I molecules of restricted distribution.

Animals↗
PubMed1999

Redundant role of the Syk protein tyrosine kinase in mouse NK cell differentiation.

Syk and ZAP-70 subserve nonredundant functions in B and T lymphopoiesis. In the absence of Syk, B cell development is blocked, while T cell development is arrested in the absence of ZAP-70. The receptors and the signaling molecules required for differentiation of NK cells are poorly characterized. Here we investigate the role of the Syk protein tyrosine kinase in NK cell differentiation. Hemopoietic chimeras were generated by reconstituting alymphoid (B-, T-, NK-) recombinase-activating gene-2 x common cytokine receptor gamma-chain double-mutant mice with Syk-/- fetal liver cells. The phenotypically mature Syk-/- NK cells that developed in this context were fully competent in natural cytotoxicity and in calibrating functional inhibitory receptors for MHC molecules. Syk-deficient NK cells demonstrated reduced levels of Ab-dependent cellular cytotoxicity. Nevertheless, Syk-/- NK cells could signal through NK1. 1 and 2B4 activating receptors and expressed ZAP-70 protein. We conclude that the Syk protein tyrosine kinase is not essential for murine NK cell development, and that compensatory signaling pathways (including those mediated through ZAP-70) may sustain most NK cell functions in the absence of Syk.

Animals↗
PubMed1999

Cutting edge: expression of functional CD94/NKG2A inhibitory receptors on fetal NK1.1+Ly-49- cells: a possible mechanism of tolerance during NK cell development.

Fetal liver- and thymus-derived NK1.1+ cells do not express known Ly-49 receptors. Despite the absence of Ly-49 inhibitory receptors, fetal and neonatal NK1.1+Ly-49- cells can distinguish between class Ihigh and class Ilow target cells, suggesting the existence of other class I-specific inhibitory receptors. We demonstrate that fetal NK1. 1+Ly-49- cell lysates contain CD94 protein and that a significant proportion of fetal NK cells are bound by Qa1b tetramers. Fetal and adult NK cells efficiently lyse lymphoblasts from Kb-/-Db-/- mice. Qa1b-specific peptides Qdm and HLA-CW4 leader peptide specifically inhibited the lysis of these blasts by adult and fetal NK cells. Qdm peptide also inhibited the lysis of Qa1b-transfected human 721.221 cells by fetal NK cells. Taken together, these results suggest that the CD94/NKG2A receptor complex is the major known inhibitory receptor for class I (Qa1b) molecules on developing fetal NK cells.

Aging↗