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Biomedical subjects

J Salinas

Publications and source records attributed to J Salinas.

At least 37 records · Page 2Linked to original sources
PubMed2000

Limited role of polymorphonuclear neutrophils in a pregnant mouse model of secondary infection by Chlamydophila abortus (Chlamydia psittaci serotype 1).

The aim of this work was to study the role of polymorphonuclear neutrophils (PMNs) in the clearance of infection, and in the development of specific immunity against Chlamydophila abortus (Chlamydia psittaci serotype 1) secondary infection. A pregnant mouse model depleted of neutrophils by the RB6-8C5 monoclonal antibody was used. No clinical signs were observed in depleted or non-depleted mice after secondary infection and no significant differences were observed in the litter size between the infected and control groups. In PMN-depleted mice C. abortus was not detected in the materno-fetal unit but merely produced low, persistent levels of infection in spleen and liver. In the non-depleted mice the level of infection was significantly lower, being resolved during the first few days post-reinfection. In both infected mice groups the immune response in the liver was quickly established and was seen to be composed mainly of CD4(+)T lymphocytes and macrophages. A Th1 response characterized by the presence of IFN-gamma and TNF-alpha in serum was observed during early infection, with significantly higher levels in the non-depleted animals. Our results suggest that PMNs have little influence on the control of C. abortus secondary infection, although they are a first line of defense and may influence the early production of TNF-alpha and IFN-gamma.

Animals↗
PubMed2000

A freezing-sensitive mutant of Arabidopsis, frs1, is a new aba3 allele.

To investigate the molecular mechanisms controlling the process of cold acclimation and to identify genes involved in plant freezing tolerance, mutations that impaired the cold acclimation capability of Arabidopsis thaliana (L.) Heynh were screened for. A new mutation, frs1 (freezing sensitive 1), that reduced both the constitutive freezing tolerance as well as the freezing tolerance of Arabidopsis after cold acclimation was characterized. This mutation also produced a wilty phenotype and excessive water loss. Plants with the frs1 mutation recovered their wild-type phenotype, their capability to tolerate freezing temperatures and their capability to retain water after an exogenous abscisic acid (ABA) treatment. Measurements of ABA revealed that frs1 mutants were ABA deficient, and complementation tests indicated that frs1 mutation was a new allele of the ABA3 locus showing that a mutation in this locus leads to an impairment of freezing tolerance. These results constitute the first report showing that a mutation in ABA3 leads to an impairment of freezing tolerance, and not only strengthen the conclusion that ABA is required for full development of freezing tolerance in cold-acclimated plants, but also demonstrate that ABA mediates the constitutive freezing tolerance of Arabidopsis. Gene expression in frs1 mutants was altered in response to dehydration, suggesting that freezing tolerance in Arabidopsis depends on ABA-regulated proteins that allow plants to survive the challenges imposed by subzero temperatures, mainly freeze-induced cellular dehydration.

Acclimatization↗
PubMed2000

Polymorphonuclear neutrophils are necessary for the recruitment of CD8(+) T cells in the liver in a pregnant mouse model of Chlamydophila abortus (Chlamydia psittaci serotype 1) infection.

The role of polymorphonuclear neutrophils (PMNs) in the development of the specific immune response against Chlamydophila abortus (Chlamydia psittaci serotype 1) infection was studied in a pregnant mouse model involving treatment with RB6-8C5 monoclonal antibody. PMN depletion significantly affected the immune response in the liver, in which the T-lymphocyte and F4/80(+) cell populations decreased, particularly the CD8(+) T-cell population. A Th1-like response, characterized by high levels of gamma interferon without detectable levels of interleukin 4 (IL-4) in serum, was observed in both depleted and nondepleted mice, although an increased production of IL-10 was detected in the depleted group. Our results suggest that PMNs play a very important role in the recruitment of other leukocyte populations to the inflammatory foci but have little influence in the polarization of the immune specific response toward a Th1-like response.

Animals↗
PubMed2000

Influence of ruminal biohydrogenation on the feeding value of fat in finishing diets for feedlot cattle.

Four Holstein steers (212 kg) with cannulas in the rumen and proximal duodenum were used in a 4 x 4 Latin square experiment to study the influence of degree of ruminal biohydrogenation (BH) on the feeding value of supplemental fat. Treatments consisted of an 88% concentrate finishing diet supplemented with 1) 2% yellow grease (control); 2) 4% formaldehyde-protected fat (Rumentek), 2% yellow grease (LBH); 3) 2% Rumentek, 4% yellow grease (MBH); or 4) 6% yellow grease (HBH). Ruminal BH of HBH, MBH, and LBH diets was 74, 68, and 54%, respectively. High-fat supplementation decreased (7%, P < .05) intestinal digestibility of 18:0 but increased intestinal digestibility of 18:1 (3%, P < .10), 18:2 (14%, P < .01), and 18:3 (23%, P < .05). Increases in intestinal digestibility of 18:0 (quadratic effect, P < .05), 18:1 (linear effect, P < .01), 18:2 (linear effect, P < .01), 18:3 (linear effect, P < .05), and total fatty acids (linear effect, P < .05) were inversely related to BH. For every 1% increase in the proportion of 18:1 fat entering the small intestine, the digestibility of 18:0 increased 1%. High-fat supplementation depressed ruminal digestion of OM (11%, P < .05), NDF (16%, P < .05), starch (6%, P < .05), and feed N (12%, P < .01). Formaldehyde-protein protection of fat diminished its depressing effects on ruminal digestion of NDF (quadratic effect, P < .10) and enhanced ruminal escape of feed N (linear effect, P < .10). Postruminal digestion of OM was greater (4.6%, P < .10) for high-fat diets. High-fat diets decreased (P < .05) total tract digestion of OM (1.9%), NDF (7.4%), and starch (.5%). Postruminal and total tract digestibility of OM, NDF, N, and starch was not affected (P > .10) by BH. In a 125-d finishing trial, 100 yearling steers (362 kg) were used to evaluate treatment effects on growth performance. High-fat diets did not affect (P > .10) ADG but increased (P < .10) feed efficiency (9%, P < .10), dietary NEm (7.6%, P < .05), and dressing percentage (9%, P < .05). The magnitude of the increase in dressing percentage was inversely related (linear effect, P < .10) to BH. We conclude that decreasing ruminal BH will increase postruminal digestibility of fat, and hence the NE value of dietary fat. The synergistic effect of increasing the proportion of 18:1 on intestinal digestion of fat enables higher levels of fat supplementation. Protecting fat from BH minimizes the detrimental effects of supplemental fat on fiber digestion.

Animal Feed↗
PubMed1999

Dimerization of Arabidopsis 14-3-3 proteins: structural requirements within the N-terminal domain and effect of calcium.

The structural requirements for dimerization of RCI14A and RCI14B, two 14-3-3 isoforms from Arabidopsis thaliana, have been analyzed by testing truncated forms of RCI14A for dimerization with full-length RCI14A and RCI14B. The results show that only the fourth helix of the truncated partner is essential for dimerization, which represents a difference from what is known for animal isoforms. On the other hand, the effect of calcium has been tested in RCI14A homodimerization. Millimolar concentrations of calcium exert a negative, dose-dependent effect that involves the C-terminal domain of RCI14A and might modulate interactions with other cellular components or among Arabidopsis 14-3-3 isoforms.

14-3-3 Proteins↗
PubMed1999

Phase II study of radiochemotherapy with UFT and low-dose oral leucovorin in patients with unresectable rectal cancer.

PURPOSE: To determine the activity and evaluate the toxicity of uracil and tegafur in a 4:1 molar concentration (UFT) plus low-dose leucovorin administered concomitantly with pelvic irradiation in patients with unresectable or recurrent rectal cancer. METHODS AND MATERIALS: Thirty-five patients (22 with primary unresectable tumors and 13 with locally recurrent tumors) were enrolled in the trial. Thirty-five patients were evaluable for toxicity and 32 of these were evaluable for clinical response. Patients received 300 mg/m2/day UFT and 30 mg/day leucovorin on days 8-35 concomitantly with pelvic radiotherapy, to a total dose of 45 Gy. RESULTS: Eight of the 35 (23%) patients developed Grade 3 diarrhea and were treated with radiotherapy alone after this event. Of the 22 patients with unresectable primary tumors, 17 underwent surgery, and resection was feasible in 15 cases (88%). Of the 32 patients evaluable for clinical response, 4 (13%) had a complete clinical response (CR) and 22 (69%) a partial response (PR). A complete pathologic response was observed in 3 cases (18%) and, a PR in 11 cases (65%). CONCLUSION: The response rates achieved with this schedule seem comparable to those obtained with 5-FU and radiotherapy. These results warrant further evaluation of this combination in patients with unresectable or locally advanced tumors.

Adult↗
PubMed1999

Identification of genes specifically expressed in cauliflower reproductive meristems. Molecular characterization of BoREM1.

Using the meristems of the cauliflower curd as a source of tissue and a series of subtractive hybridizations and amplification reactions, we have constructed a cDNA library highly enriched in cDNAs expressed in reproductive meristems. The analysis of a sample of 250 clones from this library identified 22 cDNA clones corresponding to genes specifically expressed in these cauliflower meristems. Apart from two clones that corresponded to APETALA1, and two other ones showing similarity to different aminoacyl-tRNA synthetases, the remaining clones showed no similarity to any sequence in the databases and may correspond to novel genes. One of these clones, BoREM1, was further characterized and found to correspond to a gene encoding a protein with features of regulatory proteins that follows a expression pattern very similar to the LEAFY transcripts.

Amino Acid Sequence↗
PubMed1999

Sucrose availability on the aerial part of the plant promotes morphogenesis and flowering of Arabidopsis in the dark.

Conditions to promote dark morphogenesis and flower-ing in Arabidopsis have previously been limited to liquid cultures and to a few laboratory ecotypes. We have obtained development and flowering of Arabidopsis plants under complete darkness by growing them on vertical Petri dishes containing solid agar medium with sucrose. Under these conditions, all the ecotypes tested were able to develop, giving rise to etiolated plants that flowered after producing a certain number of leaves. Dark-grown plants showed similarities with phytochrome-deficient mutants and were different from de-etiolated or constitutive photomorphogenesis mutants such as det and cop. Late- and early-flowering ecotypes, showing large differences in flowering time and leaf number under long days, flowered with a similar number of leaves when grown in the dark. Rapid dark flowering of late-flowering ecotypes was not an effect of darkness but the result of the interaction between dark and sucrose availability at the aerial part of the plant, since sucrose also had an effect when plants were grown in the light. Gibberellin-deficient and insensitive mutants were delayed in the initiation of flowers in the dark, indicating a role for these hormones in flowering promotion in the dark. The late-flowering phenotype of mutants at different loci of the autonomous and long-day-dependent flowering induction pathways was rescued in dark growth conditions. However, the late-flowering phenotype of ft and fwa mutants was not rescued by sucrose either in the dark or in the light, suggesting a different role for these genes in flowering induction.

Arabidopsis↗
PubMed1999

The Arabidopsis CBF gene family is composed of three genes encoding AP2 domain-containing proteins whose expression Is regulated by low temperature but not by abscisic acid or dehydration.

We have identified two genes from Arabidopsis that show high similarity with CBF1, a gene encoding an AP2 domain-containing transcriptional activator that binds to the low-temperature-responsive element CCGAC and induces the expression of some cold-regulated genes, increasing plant freezing tolerance. These two genes, which we have named CBF2 and CBF3, also encode proteins containing AP2 DNA-binding motifs. Furthermore, like CBF1, CBF2 and CBF3 proteins also include putative nuclear-localization signals and potential acidic activation domains. The CBF2 and CBF3 genes are linked to CBF1, constituting a cluster on the bottom arm of chromosome IV. The high level of similarity among the three CBF genes, their tandem organization, and the fact that they have the same transcriptional orientation all suggest a common origin. CBF1, CBF2, and CBF3 show identical expression patterns, being induced very rapidly by low-temperature treatment. However, in contrast to most of the cold-induced plant genes characterized, they are not responsive to abscisic acid or dehydration. Taken together, all of these data suggest that CBF2 and CBF3 may function as transcriptional activators, controlling the level of low-temperature gene expression and promoting freezing tolerance through an abscisic acid-independent pathway.

Abscisic Acid↗
PubMed1999

Role of polymorphonuclear neutrophils in a murine model of Chlamydia psittaci-induced abortion.

To assess the role of polymorphonuclear neutrophils (PMNs) in Chlamydia psittaci infection in a pregnant mouse model, pregnant and nonpregnant Swiss OF1 mice were depleted of PMNs by treatment with the RB6-8C5 monoclonal antibody before intraperitoneal infection with C. psittaci serotype 1. Nondepleted mice served as infection controls. Depleted mice aborted earlier and had a much higher mortality rate than nondepleted mice. Bacteriological analysis showed that the number of chlamydiae isolated from the spleens of depleted mice at 5 and 7 days postinfection was 100 times greater than that isolated from nondepleted mice. Histopathological analysis of the placentas of depleted mice showed widespread necrosis of the uteroplacental units, with weak immunoreaction to chlamydial antigen, while the placentas of nondepleted mice showed substantial neutrophil infiltration but no large areas of necrosis, with moderate to strong immunoreaction to chlamydial antigen. The livers of depleted mice showed numerous chlamydial inclusions in the hepatocytes, delayed microgranuloma formation, and in the pregnant animals extensive coagulative periportal necrosis. The livers of nondepleted mice displayed multiple small foci of PMNs and mononuclear cells with microgranuloma formation. Among this group of mice, the pregnant animals always had more hepatic damage than nonpregnant animals. Our results suggest that PMNs play an essential role in the response to C. psittaci primary infection, preventing the uncontrolled multiplication of chlamydiae in the liver and spleen.

Abortion, Veterinary↗
PubMed1999

Prognostic value of ornithine decarboxylase and polyamines in human breast cancer: correlation with clinicopathologic parameters.

The polyamines putrescine, spermidine, and spermine and ornithine decarboxylase (ODC), the rate-limiting enzyme in their biosynthetic pathway, play an important role in cell proliferation, differentiation, and transformation. In the present study, we have analyzed polyamine concentrations and ODC activity in samples from benign breast diseases (n = 36), benign breast tissue adjacent to the primary carcinoma (n = 19), and breast carcinoma (n = 104). ODC activity in primary carcinoma was significantly higher (2.42 +/- 0.22 nmol CO2/h g; P < 0.001) than that found in benign breast (0.62 +/- 0.15 nmol CO2/h g) or in breast tissue adjacent to the primary carcinoma (0.52 +/- 0.16 nmol CO2/h g). The total polyamine content of breast cancer tissues was higher than in benign breast diseases (704.3 +/- 38.3 nmol/g wet weight versus 295.8 +/- 27.4 nmol/g wet weight) and correlated well with ODC activity (Pearson, r = 0.42; P < 0.001). ODC activity correlated with histological grade, peritumoral lymphatic or blood vessel invasion, S-phase fraction, and cathepsin D. Total polyamine concentration increased with S-phase fraction, cathepsin D, and aneuploidy. No significant correlation was found between ODC or polyamines and tumor size, lymph node involvement, or steroid receptor status. A major finding in our study was that ODC activity was an independent prognostic factor for recurrence and death. The results indicate that the estimation of ODC activity and polyamines in human breast carcinoma might be useful to determine tumor aggressiveness and suggest that ODC may have a potential value as both a prognostic factor and a chemoprevention target in human breast cancer.

Adolescent↗
PubMed1998

Expression of immunogenic glycoprotein S polypeptides from transmissible gastroenteritis coronavirus in transgenic plants.

The use of transgenic plants as vaccine production systems was described recently. We report on the immunological response elicited by two recombinant versions of the glycoprotein S from the swine-transmissible gastroenteritis coronavirus (TGEV) expressed in transgenic plants. Arabidoposis plants were genetically transformed with cDNAs constructs encoding either the N-terminal domain (amino acid residues 1-750) or the full-length glycoprotein S of TGEV, responsible for the neutralizing antibody induction against the virus, under the control of the cauliflower mosaic virus 35S (CaMV 35S) promoter. Genomic DNA and mRNA analyses of leaf extracts from transformed plants demonstrated the incorporation of the foreign cDNA into the arabidopsis genome, as well as their transcription. Expression of recombinant polypeptides were observed in most transgenic plants by ELISA using specific antibodies. Mice immunized with leaf extracts from transgenic plants developed antibodies that reacted specifically with TGEV in ELISA, immunoprecipitated the virus-induced protein, and neutralized the virus infectivity. From these results, we conclude that transgenic plants expressing glycoprotein S polypeptides may possibly be used as a source of recombinant antigen for vaccine production.

Animals↗
PubMed1998

Low temperature regulates Arabidopsis Lhcb gene expression in a light-independent manner.

Low temperature treatment of dark-grown seedlings of Arabidopsis thaliana results in a rapid increase in the amount of mRNAs encoding for the major polypeptides of the light-harvesting complex of photosystem II (Lhcb1 genes). This increase is transient and seems to be due mainly to the accumulation of Lhcb1*3 transcripts, indicating that low temperature differentially regulates the expression of the Arabidopsis Lhcb1 gene family in the dark. A 1.34 kb fragment of the Lhcb1*3 promoter is sufficient to confer low temperature regulation to a reporter gene in transgenic Arabidopsis etiolated seedlings, suggesting that the regulation is occurring at the transcriptional level. The cold-induced accumulation of Lhcb1*3 mRNA is not part of a general response to stressful conditions since no accumulation is detected in response to water stress, anaerobiosis or salt stress. The amount of Lhcb1*3 mRNA decrease in response to exogenous abscisic acid (ABA) suggesting that this phytohormone acts as a negative regulator. Moreover, the accumulation of Lhcb1*3 mRNAs in cold-treated ABA deficient etiolated seedlings is higher than that of wild-type and ABA insensitive etiolated seedlings, indicating that low temperature regulation of Lhcb1*3 is not mediated by ABA.

Abscisic Acid↗
PubMed1998

Isolation and molecular characterization of the Arabidopsis TPS1 gene, encoding trehalose-6-phosphate synthase.

An Arabidopsis thaliana cDNA clone, AtTPS1, that encodes a trehalose-6-phosphate synthase was isolated. The identity of this protein is supported by both structural and functional evidence. On one hand, the predicted sequence of the protein encoded by AtTPS1 showed a high degree of similarity with trehalose-6-phosphate synthases of different organisms. On the other hand, expression of the AtTPS1 cDNA in the yeast tps1 mutant restored its ability to synthesize trehalose and suppressed its growth defect related to the lack of trehalose-6-phosphate. Genomic organization and expression analyses suggest that AtTPS1 is a single-copy gene and is expressed constitutively at very low levels.

Amino Acid Sequence↗
PubMed1998

Tomato flower abnormalities induced by low temperatures are associated with changes of expression of MADS-Box genes

Flower and fruit development in tomato (Lycopersicon esculentum Mill. ) were severely affected when plants were grown at low temperatures, displaying homeotic and meristic transformations and alterations in the fusion pattern of the organs. Most of these homeotic transformations modified the identity of stamens and carpels, giving rise to intermediate organs. Complete homeotic transformations were rarely found and always affected organs of the reproductive whorls. Meristic transformations were also commonly observed in the reproductive whorls, which developed with an excessive number of organs. Scanning electron microscopy revealed that meristic transformations take place very early in the development of the flower and are related to a significant increase in the floral meristem size. However, homeotic transformations should occur later during the development of the organ primordia. Steady-state levels of transcripts corresponding to tomato MADS-box genes TM4, TM5, TM6, and TAG1 were greatly increased by low temperatures and could be related to these flower abnormalities. Moreover, in situ hybridization analyses showed that low temperatures also altered the stage-specific expression of TM4.

Journal Article↗
PubMed1998

Kinetics of infection and effects on placental cell populations in a murine model of Chlamydia psittaci-induced abortion.

The anatomical progression of chlamydial infection was studied in different areas of the placenta, using a mouse model and two inoculation times: early pregnancy (day 7, group A) and midpregnancy (day 11, group B). The first population cells affected were decidual cells and neutrophils located just at the limits of the maternal and fetal placenta. The following invaded area was the layer of giant cells. Complete colonization of the maternal placenta occurred after day 15 of pregnancy independently of the inoculation time, the metrial gland being the last area to be invaded; numerous granulated metrial gland (GMG) cells were infected. Finally, chlamydial inclusions were observed in labyrinthine trophoblastic cells from day 18 of pregnancy onward. Since no fetal damage was observed, it seems that an indirect mechanism involving the lysis of GMG cells and neutrophil infiltration of the decidua and metrial gland may be the pathogenic mechanism that leads to abortion.

Abortion, Veterinary↗
PubMed1998

Protective immune response to foot-and-mouth disease virus with VP1 expressed in transgenic plants.

It has been reported recently that genes encoding antigens of bacterial and viral pathogens can be expressed in plants in a form in which they retain native immunogenic properties. The structural protein VP1 of foot-and-mouth disease virus (FMDV), which has frequently been shown to contain critical epitopes, has been expressed in different vectors and shown to induce virus-neutralizing antibodies and protection in experimental and natural hosts. Here we report the production of transformed plants (Arabidopsis thaliana) expressing VP1. Mice immunized with leaf plant extracts elicited specific antibody responses to synthetic peptides representing amino acid residues 135 to 160 of VP1, to VP1 itself, and to intact FMDV particles. Additionally, all of the immunized mice were protected against challenge with virulent FMDV. To our knowledge, this is the first study showing protection against a viral disease by immunization with an antigen expressed in a transgenic plant.

Animals↗