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F Ramírez

Publications and source records attributed to F Ramírez.

At least 19 recordsLinked to original sources
PubMed2006

Reactions, characterization and uptake of ammoxidized kraft lignin labeled with 15N.

Ammoxidation of kraft lignin was carried out in a Parr reactor using (15)NH(3) as the main nitrogen source. Reaction parameters were set up until a total nitrogen content of approximately 13 wt.% in lignin was achieved, in accordance with conditions of previous studies. Analytical tools such as FTIR, Py-GC/MS, and solid state NMR were used in this research. The nature of nitrogen bondings is discussed. The incorporation of the (15)N from ammoxidized lignin was followed in pumpkins (Zucchini cucurbita pepo L.) by means of (15)N emission spectroscopy.

Ammonia↗
PubMed2004

Sulphide and oxygen inhibition over the anaerobic digestion of organic matter: influence of microbial immobilization type.

Two different types of microbial aggregates (granular sludge and biofilm onto a plastic matrix) were evaluated for their susceptibility to sulphide and dissolved oxygen. Their specific methanogenic and sulphate reducing activities were evaluated separately and simultaneously. Total sulphide concentrations that caused 50% loss of methanogenic activity were 800 and 1250 mg l(-1) and for sulphate reduction 750 and 860 mg l(-1) for the granular sludge and the attached biomass, respectively. Simultaneous methanogenesis and sulphate reduction resulted in an increased tolerance of the sulphate reducing process towards sulphide. Results suggest that methanogenesis in granular sludge is less resistant to sulphide than in the attached biomass structure, whereas in sulphate reduction the attached biomass exhibited a better tolerance to high concentrations of total sulphide than the granular sludge. The better sulphate reducing capacity in the attached biomass may suggest that biomass was selectively attached. The dissolved oxygen concentration that inhibited 50% the methanogenic activity was 4.9 and 6.4 mg l(-1) for the granular sludge and attached biomass, respectively. When methanogenesis and sulphate reduction were carried out simultaneously, the whole process was not affected by the supplied oxygen, as produced sulphide was used by sulphide oxidizing microorganisms thus scavenging oxygen. Results showed that the integration of anaerobic/aerobic conditions in a single bioreactor is quite possible and can be used as a good strategy for the complete transformation of sulphate to elemental sulphur.

Bacteria, Aerobic↗
PubMed2003

Anti-chromatin antibodies in systemic lupus erythematosus: a useful marker for lupus nephropathy.

BACKGROUND: Anti-chromatin antibodies have recently been described in patients with systemic lupus erythematosus (SLE) and it has been suggested that their presence is associated with lupus nephritis. OBJECTIVE: To assess the prevalence and clinical associations of these antibodies in SLE. METHODS: The presence of anti-chromatin antibodies in 100 patients with SLE was investigated by an enzyme linked immunosorbent assay (ELISA). To determine the specificity of these antibodies, 100 patients with primary Sjögren's syndrome, 30 with primary antiphospholipid syndrome (APS), 10 with systemic sclerosis, and 100 normal controls were also tested. RESULTS: Positive levels were detected in 69/100 (69%) patients with SLE. In contrast, they were found in only 8/100 (8%) of those with primary Sjögren's syndrome, in 1/10 (10%) with systemic sclerosis, in 2/30 (7%) with primary APS, and in none of the 100 healthy controls. Patients with anti-chromatin antibodies had a twofold higher prevalence of lupus nephropathy than those without these antibodies (58% v 29%, p<0.01). A significant correlation was found between the levels of anti-chromatin antibodies and disease activity score as measured by the European Consensus Lupus Activity Measurement (ECLAM; p=0.011). CONCLUSIONS: The measurement of anti-chromatin antibodies appears to be a useful addition to the laboratory tests that can help in the diagnosis and treatment of SLE. These antibodies are both sensitive and specific for SLE, and are a useful marker for an increased risk of lupus nephritis.

Adolescent↗
PubMed2001

Biomechanical and biochemical pulping of sugarcane bagasse with Ceriporiopsis subvermispora fungal and xylanase pretreatments.

Sugarcane bagasse was pretreated with both the white-rot fungus, Ceriporiopsis subvermispora, and xylanase enzyme for 2 weeks before soda chemithermomechanical (CTMP) and soda chemical (CP) cooking. For fungi-CTMP (BCTMP) and enzyme-fungi-CTMP (EBCTMP), the bagasse, after bio-pretreatment, was cooked with 5% sodium hydroxide, at 130 degrees C for 20 min. For the chemical pulping (CP), after fungi pretreatment (BCP) or after xylanase and fungal pretreatment (EBCP), the bagasse was cooked with 14.5% sodium hydroxide. With the BCTMP, the Klason lignin was reduced, all of the pulp strength properties were increased, and a 28% savings in refining energy consumption was obtained, but the brightness was reduced 5 points compared to the control. With the EBCTMP, the brightness losses were overcome but with a mild reduction in the pulp strength properties compared to the BCTMP. The energy savings were 5% greater than from BCTMP and 33% over the control. The BCP treatment increases somewhat the pulp strength properties, reduces the energy consumption 23%, and reduces the brightness by 9 points compared to the control; however, the kappa no. was 5.5 points higher than the control. EBCP treatment reduces brightness losses and increases the pulp yield 2% compared to the control, but with some reduction in the strength properties compared to BCP.

Basidiomycota↗
PubMed2001

Suicide attempts in bipolar patients.

BACKGROUND: Between 25% to 50% of patients with bipolar disorder make suicide attempts during their lives, but there are some controversies about factors related to suicide attempts in this group of patients. The aim of this study is to investigate the association between suicide attempts and the predictive factors previously described in the literature. METHOD: The sample included all 169 patients with DSM-III-R bipolar I disorder identified in a delimited area (northern Spain). Sociodemographic, clinical, and family history variables measured by Research Diagnostic Criteria-Family History were analyzed. Significant variables were introduced in a logistic regression analysis to control for the effects of other variables. RESULTS: There were 56 patients (33%) who had one or more suicide attempts. Early age at onset, history of hospital admission during depressive episodes, drug abuse, and family history were significantly associated with suicide in the univariate analyses (p < .05). A much higher proportion of patients with onset at or before 25 years of age than patients with onset after 25 years of age attempted suicide (23% vs. 10%). The age at onset was no longer significant after controlling for the other 3 variables included in the logistic regression analysis. CONCLUSION: Suicide attempts are highly prevalent in bipolar patients and are related to drug abuse, family history of affective disorders, and severe depressive episodes. This study suggests that the risk of suicide in patients with an early age at onset could reflect other variables such as drug abuse, a history of hospital admissions for depression, or family history.

Adolescent↗
PubMed2000

Recirculatory and sessile CD4+ T lymphocytes differ on CD45RC expression.

CD4+ T cell subsets are unequally distributed in rat secondary lymphoid organs. Those with the memory phenotype CD45RClow Thy-1- L-selectin- are present at a higher frequency in Peyer's patches (PP) than in lymph nodes and spleen, and increase in numbers with age in all three tissues, particularly in the PP. Homing experiments revealed that CD4+ T cells that recirculate through secondary lymphoid organs are mainly CD45RChigh. It was also apparent that the ability of recirculating cells to enter different lymphoid organs varies; less cells enter PP than the spleen or lymph nodes. Our results also reveal the existence of a nonrecirculating population of CD4+ T cells in secondary lymphoid organs, which are predominantly, if not exclusively, CD45RClow. Our results show that secondary lymphoid organs differ in their CD4+ T cell subset composition as a consequence of having different ratios of recirculatory:nonrecirculatory CD4+ T cells, and these cells display a different CD45RC phenotype.

Animals↗
PubMed2000

Induction of resistance to active experimental allergic encephalomyelitis by myelin basic protein-specific Th2 cell lines generated in the presence of glucocorticoids and IL-4.

We have produced T cell lines with a Th2 phenotype in the presence of IL-4 and the glucocorticoid dexamethasone (DEX). IL-4 and DEX together were more effective in inducing a Th2 response than IL-4 alone. Myelin basic protein (MBP)-specific Th2 lines were obtained and their ability to induce experimental allergic encephalomyelitis (EAE) was studied. Lines treated with IL-4 and DEX did not transfer passive EAE and did not induce cellular infiltration into the central nervous system as opposed to the encephalitogenic Th1 lines. Lines treated with IL-4 and DEX did not protect animals from the effect of encephalitogenic Th1 lines when the two were injected together. However, a high proportion of animals injected with IL-4 + DEX-treated lines became refractory to the development of EAE after immunization with MBP; that is, it was possible to induce resistance to active EAE without prior episodes of disease. Interestingly, animals injected with T cell lines had accelerated antibody responses against MBP and the predominant isotype was dependent on the cytokines synthesized by the T cell line injected. There was not evidence that the resistance to active EAE was due to anergy of MBP-reactive cells or the action of CD8+ cells. Our data suggest that MBP-specific T cell lines prevent the induction of disease by deviating the reactivity to MBP from a cell-mediated to a humoral one and not merely from a Th1 to a Th2 response.

Adoptive Transfer↗
PubMed2000

Phenotypic analysis of peripheral CD4+ CD8+ T cells in the rat.

Among peripheral T cells, the expression of CD4 and CD8 is almost mutually exclusive. However, here we show, using flow cytometric analysis, that ex vivo approximately 6% of rat T cells stained for both CD4 and CD8. These double positive cells were also detected by confocal microscopy. Only around 50% of double positive cells expressed the CD8beta chain, the remaining cells expressed the CD8alpha chain alone. Double positive cells were blast-like with a phenotype, distinct from that of either CD4 or CD8 single positive cells, suggestive of an activated state. Previous reports of double positive T cells have also suggested that coexpression of CD4 and CD8 is linked to the activation state of the cell. There was an indication that priming animals with a hapten-carrier complex increased the ratio of CD8alphaalpha : alphabeta expressing double positive T cells, although we did not detect an increase in the frequency of double positive T cells following priming. We also show that the frequency of double positive cells was reduced following thymectomy and with age. In conclusion, these studies show that peripheral T cells expressing both CD4 and CD8 can be detected in the rat and that they are phenotypically distinct from CD4 and CD8 single positive T cells.

Aging↗
PubMed1998

Rat interleukin-4 assays.

The present article describes procedures to measure rat IL-4 protein. The RT-PCR technique has been successfully and widely used to measure IL-4 mRNA, but it does not determine IL-4 protein synthesis. Assays to measure rat IL-4 protein based on its biological activity were developed using the mAb OX-81, which inhibits rat IL-4 activity. Two bioassays were attempted based on the ability of IL-4 to induce the proliferation of T cell blasts and to increase MHC class II expression on resting B cells. A second mAb against rat IL-4 was used in a sandwich ELISA to detect rat IL-4. This ELISA is satisfactory although its sensitivity is not as high as that of the bioassay. According to our experience, the bioassay based on the induction of class II MHC molecules on B cells is the technique of choice for rat IL-4 determination because it proved specific, sensitive and reproducible.

Animals↗
PubMed1998

Glucocorticoids induce a Th2 response in vitro.

Purified rat CD4+ T cells were activated in vitro, by the polyclonal mitogen Concanavalin A (Con A) or by mixed lymphocyte reaction (MLR), in the presence or absence of the glucocorticoid dexamethasone (DEX). They were then expanded in IL-2 and subsequently restimulated, this time in the absence of the hormone. The results indicate that the exposure of the cells to DEX in the primary stimulation changed the cytokine synthesis induced by the secondary stimulation. IL-4 production was increased by the pretreatment whereas synthesis of IFN-gamma was diminished. Addition of DEX in the second activation suppressed all cytokine production. In brief, the transient presence of glucocorticoids in the culture induces a change in the pattern of cytokine production but the continuous presence causes inhibition of cytokine synthesis. Further studies in which IL-4 was used together with DEX showed that the cytokine potentiated the effect of the hormone. The data here presented suggest that glucocorticoids and the neuroendocrine system may be expected to have long-term immunological effects as well as short-lived immunosuppressive ones. High concentration of glucocorticoids suppress cytokine production but when steroids return to basal levels the immune response is directed in a way that favors Th2-type reactions. Possible implications regarding the immune response to pathogens and autoantigens are discussed.

Animals↗
PubMed1997

Glucocorticoids enhance concanavalin A-induced mitogenic response through the inhibition of nitric oxide production.

Glucocorticoids (GC) are known to inhibit mitogen-induced proliferation of T cells. In this study we show two experimental situations where the addition of GC increases lymphocyte proliferation. It has been reported by different authors that rat spleen (SPL) cells proliferate poorly after concanavalin A (Con A) activation. These poor responses have been related to the suppressor activity of macrophages. Similarly, it is known that T-cell proliferation is depressed in the presence of an excess of macrophages in the culture. Here we show that in both experimental situations, the inclusion of dexamethasone (DEX), a synthetic glucocorticoid, in the culture medium enhances the Con A-stimulated proliferation. We provide evidence that this effect is a consequence of the inhibition of nitric oxide (NO) synthesis by the hormone. Furthermore, we also demonstrate that rat SPL cells are inefficient antigen-presenting cells (APC) because of their spontaneous high production of NO. Taken together our results suggest that the effects of GC on T-cell activation may be to promote or inhibit proliferation depending on the level of endogenous NO synthesis. The possible significance of these results is briefly discussed.

Animals↗
PubMed1996

Glucocorticoids promote a TH2 cytokine response by CD4+ T cells in vitro.

Purified rat CD4+ T cells were activated in vitro in the presence or absence of the glucocorticoid dexamethasone. They were then expanded in IL-2 and subsequently restimulated, this time in the absence of the hormone. The results indicate that the exposure of the cells to dexamethasone in the primary stimulation changed the cytokine synthesis induced by the secondary stimulation. The mRNA levels for IL-4, IL-10, and IL-13 were all increased by the pretreatment, whereas synthesis of IFN-gamma and TNF-alpha was diminished. Further studies in which IL-4 was used together with dexamethasone showed that the cytokine potentiated the effect of the hormone. These data suggest that the neuroendocrine system can influence the cytokine response to pathogens and autoantigens in a way that favors Th2-type reactions. There are similar implications for therapy with glucocorticoids, and these drugs may be expected to have long term immunologic effects as well as short-lived immunosuppressive ones. The production of a mouse mAb, MRC-OX81, against rat IL-4 is also described.

Animals↗
PubMed1992

[Invasive mole with uterine rupture].

A case of chorioadenoma destruens with uterine rupture is reported. The patient was admitted because a persistent uterine bleeding after abortion about two months before. The titulation of gonadotrophic hormone resulted in 25,000 unities. After curettage she was complicated with hemoperitoneum and went to surgery. During hysterectomy were identified trophoblastic tissue in the broad ligament and partial blocking of the right ureter. After repeated chemotherapy she presented severe immuno depression and sepsis complicated with hemopericardium and died five months after the first admission. The pathology study demonstrated a perforation because a trophoblastic invasion in the right side of the cervix and in the autopsy was demonstrated right ureteral obstruction due to a fibro necrotic an inactive trophoblastic tissue determining significant right hydro-uretero nephrosis.

Adult↗
PubMed1991

[The surgical treatment of anterior hypospadias. Apropos 590 cases (1966-1988). The indications and results. The current trends in surgical treatment].

The surgical treatment of hypospadias is very complex. The objective is to obtain a satisfactory urinary and genital function with an equal morphological, anatomical and aesthetic result. Our contribution covers twenty-two years of surgical multicentre experience (590 cases). We evaluate the surgical indication, results, complications, associated malformations and study protocols. We have objectively evaluated the evolution of the indications, as well as the application of different techniques depending on the extent of urethral malformation.

Child↗
PubMed1990

OX48, a monoclonal antibody against a 70,000 MW rat activation antigen expressed by T cells bearing the high-affinity interleukin-2 receptor.

The monoclonal antibody (mAb) OX48 recognizes a 70,000 MW cell-surface protein present in a small percentage of activated rat T cells and in CD8+ rat x BW5147 interleukin-2 (IL-2)-dependent T-cell hybridomas, but not in resting spleen cells or in IL-2-independent T-cell hybrids. OX48 antibody added simultaneously with concanavalin A (Con A) to resting spleen cells inhibits the cell proliferation and reduces the IL-2 production. However, addition of IL-2 does not restore the mitogenic response. Growth of rat blast T cells or IL-2-dependent hybrids is not affected by the OX48 antibody. There is a close correlation between the expression of high-affinity IL-2 receptors (IL-2R) and the OX48 antigen in T-cell hybridomas. In spite of this striking correlation, OX48 mAb does not inhibit the binding of 125I-IL-2 to the IL-2-dependent hybrids, and is unable to immunoprecipitate any of the proteins chemically cross-linked to 125I-IL-2. Therefore, the OX48 molecule represents a new rat activation antigen, undefined in other species, and probably involved in the early steps of T-cell activation.

Animals↗
PubMed1989

Tooth pulp stimulation advances both medullary off-cell pause and tail flick.

It has been postulated that the so-called off-cells of nucleus raphe magnus and adjacent structures in the rat are the output elements of a system which inhibits nociceptive transmission at the spinal cord. Off-cells stop firing about 0.4 s before the tail flick reflex (TF) elicited by the application of noxious heat to the tail. When continuous off-cell activity is induced by either morphine injection or periaqueductal gray stimulation, the TF is delayed. The present results show that electrical stimulation of the tooth pulp (TP) causes the off-cells to stop firing. Furthermore, when TP is stimulated during tail heating and before the expected time for TF, off-cells stop firing earlier and the TF occurs also earlier. This supports the notion that off-cells inhibit nociceptive transmission.

Animals↗