Descripción: 1. 1. Porphyrin biosynthesis from 5-aminoevulinic acid (ALA) was investigated using the technique of tissue explant cultures, in both human breast cancer and its original normal tissue. 2. 2. The activity of ALA-dehydratase, porphobilinogenase and uroporphyrinogen decarboxylase was directly determined in both tumor and normal mammary tissues. 3. 3. Porphyrin synthesis capacity of human breast carcinoma was 20-fold enhanced, as compared with normal tissue, at least between the stages of porphobilinogen and coproporphyrinogen formation. 4. 4. The activity of the three enzymes examined was always lower in normal tissue than in tumoral tissue. 5. 5. Present findings show that porphyrin biosynthesis is increased in breast cancer tissue. © 1990.

Descripción: We have described a method for preparation of [10B]-enriched-8- dihydroxyborylharmine (III) and characterized it by their spectral properties (MS, IR and NMR). This compound is a potential BNCT agent.

Descripción: We present experimental measurements and theoretical predictions of ion transport in agar gels during reversible electroporation (ECT) for conditions typical to many clinical studies found in the literature, revealing the presence of pH fronts emerging from both electrodes. These results suggest that pH fronts are immediate and substantial. Since they might give rise to tissue necrosis, an unwanted condition in clinical applications of ECT as well as in irreversible electroporation (IRE) and in electrogenetherapy (EGT), it is important to quantify their extent and evolution. Here, a tracking technique is used to follow the space-time evolution of these pH fronts. It is found that they scale in time as t1/2 characteristic of a predominantly diffusive process. Comparing ECT pH fronts with those arising in electrotherapy (EChT), another treatment applying constant electric fields whose main goal is tissue necrosis, a striking result is observed: anodic acidification is larger in ECT than in EChT, suggesting that tissue necrosis could also be greater. Ways to minimize these adverse effects in ECT are suggested. © 2011 Turjanski et al.

Descripción: This paper reports the standardization of methods used for processing and embedding various vertebrate brains of different sizes in paraffin. Other technical details developed for avoiding frequent difficulties arising during laboratory routine are also reported. Some modifications of the Nissl and Klüver-Barrera staining methods are proposed. These modifications include: 1) a Nissl stain solution with a rapid and efficient action with easier differentiation; 2) the use of a cheap microwave oven for the Klüver-Barrera stain. These procedures have the advantage of permitting Nissl and Klüver-Barrera staining of nervous tissue in about five and fifteen minutes respectively. The proposed procedures have been tested in brains obtained from fish, amphibians, reptiles and mammals of different body sizes. They are the result of our long experience in preparing slides for comparative studies. Serial sections of excellent quality were regularly obtained in all the specimens studied. These standardized methods, being simple and quick, are recommended for routine use in neurobiological laboratories.

Descripción: Five disulfated steroids and a mixture of monosulfated steroids were isolated from the ethanolic extract of the antarctic ophiuroid Gorgonocephalus chilensis. The structures were determined by 1H-NMR, 13C-NMR and FABMS.

Descripción: Comparative studies on fatty acid and protein composition of the endosperm and embryo of palmito (Euterpe edulis Martius) were conducted using gas-liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. On a dry weight basis, the embryo contained extremely lower amounts of lipids and proteins than did the endosperm, which was associated with the scarce lipid and protein bodies previously reported in axis and cotyledon. The fatty acid composition also exhibited differences between both tissues: (I) the fatty acid diversity was greater in embryo than in endosperm; (II) embryo and endosperm contained predominantly linoleic, palmitic, oleic and stearic acids even though the relative values were different for each tissue. As compared to other palm species, the higher fatty acid unsaturation in Euterpe edulis seed could be involved in the previously reported short longevity and recalcitrant behavior during storage. Proteins of both tissues were heterogeneous in molecular mass. Some proteins were tissue-specific, but other were common, among them a highly glycosylated protein which migrated at about 55 kDa. We hypothesize that the latter, also reported in all previously studied palm species, is one of the proteins characterizing the Arecaceae family.

Descripción: The use of 5-aminolaevulinic acid (ALA) is gaining increasing attention for photosensitization in photodynamic therapy of superficially localized tumours. The aim of this work was to determine the kinetics of porphyrin generation in tissues after topical application of ALA delivered in different vehicles on the skin overlying the tumour and normal skin of mice. Maximal accumulation was found in tumour 3 h after ALA application in both cream and lotion preparations. Normal and overlying tumour skin tissues showed different kinetic patterns, reflecting histological changes when the latter is invaded by tumour cells. Liver, kidney, spleen and blood porphyrins also raised from basal levels, showing that ALA and/or ALA-induced porphyrins reach all tissues after topical application. During the first 24 h of ALA topical application, precursors and porphyrins are excreted by both urine and faeces. ALA lotion applied on the skin overlying the tumour induced higher accumulation of tumoural porphyrins than cream, and lotion applied on normal skin appeared to be the most efficient upon inducing total body porphyrins. This work has demonstrated the great influence of the formulation of ALA vehicle on penetration through the skin. Knowledge of the kinetics of porphyrin generation after different conditions of ALA application is needed for the optimization of diagnosis and phototherapy in human tumours.

Descripción: The aims of this study were to investigate the negative action of leptin on some intraovarian ovulatory mediators during the ovulatory process and to assess whether leptin is able to alter the expression of its ovarian receptors. Immature rats primed with gonadotrophins were used to induce ovulation. Serum leptin concentration was diminished 4 h after human chorionic gonadotrophin (hCG) administration, whereas the ovarian expression of leptin receptors, measured by western blot, was increased by the gonadotrophin treatment. Serum progesterone level, ovulation rate and ovarian prostaglandin E (PGE) content were reduced in rats primed with equine chorionic gonadotrophin (eCG)/hCG and treated with acute doses of leptin (five doses of 5 μg each). These inhibitory effects were confirmed by in vitro studies, where the presence of leptin reduced the concentrations of progesterone, PGE and nitrites in the media of both ovarian explants and preovulatory follicle cultures. We also investigated whether these negative effects were mediated by changes in the expression of the ovarian leptin receptors. Since leptin treatment did not alter the expression of ovarian leptin receptor, the inhibitory effect of leptin on the ovulatory process may not be mediated by changes in the expression of its receptors at ovarian level, at least at the concentrations assayed. In summary, the ovulatory process was significantly inhibited in response to an acute treatment with leptin, and this effect may be due, at least in part, to the direct or indirect impairment of some ovarian factors, such as prostaglandins and nitric oxide. © 2006 Society for Reproduction and Fertility.

Descripción: 1. 1. Effects of various factors on chlorophyll, porphyrin and protein content, growth and on the activities of the enzymes involved in the earlier stages of tetrapyrrole synthesis, in cultured soybean cells, were studied. 2. 2. When dark-grown callus was exposed to light, it was found that the amount of porphyrins formed was not altered, but chlorophyll content as well as Succinyl CoA Synthetase (Suc.CoA-S), Aminolevulic Acid Synthetase (ALA-S), Aminolevulic Acid Dehydratase (ALA-D) and Porphobilinogenase (PBGase) activities increased. 3. 3. Addition of Aminolevulic Acid (ALA) to the medium culture, was found to stimulate porphyrin accumulation and to prevent growth; however chlorophyll content was not significantly modified. ALA-S was inhibited while both ALA-D and PBGase activities were enhanced. The action of puromycin and mitomycin added along with ALA to the media, was also studied, but neither of these inhibitors modified much the effects produced by ALA. 4. 4. Addition of Porphobilinogen (PBG), showed accumulation of uroporphyrin in the tissue; except inhibition of ALA-S, enzymes activities, protein and chlorophyll content were not modified. Evidence obtained would indicate that callus tissue was not permeable to PBG. 5. 5. Omission of iron from the culture medium, produced porphyrin accumulation and prevented growth. It has been consistently found that, the higher the content of porphyrins, the less the callus growth. Coproporphyrin was the major component of the porphyrins formed in ALA supplemented or iron deficient media. ALA-S and ALA-D were reduced under iron deficiency. 6. 6. The addition of ATP to the media, did not affect porphyrin, protein, and chlorophyll synthesis, growth or ALA-D, but Suc.CoA-S, ALA-S and PBGase activities diminished. 7. 7. Gibberelic acid produced a measurable increase of PBGase, while diminished Suc.CoA-S and ALA-S. 8. 8. Succinate increased growth and inhibited ALA-S and ALA-D. 9. 9. Carbonyl cyanide m-chlorophenyl hydrazine (CCCP), added to the medium produced accumulation of porphyrins, consequently, ALA-S was greatly inhibited and growth prevented. PBGase was also diminished. 10. 10. Coproporphyrinogenase and Decarboxylases activities were hardly detected in most experiments, and are limiting. 11. 11. The complex pattern of results obtained is discussed. © 1975.

Descripción: Trypanosoma cruzi, the agent of Chagas disease contains a major cysteine proteinase, cruzipain (Cz), with an unusual carboxyl-terminal extension (C-T). We have previously reported the presence of sulfate groups in the N-linked oligosaccharide chains of this domain. In order to evaluate the immune responses to sulfated moieties on Cz, BALB/c mice were immunized with purified Cz and C-T prior and after desulfation treatment. The humoral immune response to sulfates on Cz or C-T was mainly IgG2b. Interestingly, the abolishment of IgG2b reactivity when desulfated antigens were used as immunogens demonstrates that esterified sulfate groups are absolutely required for eliciting IgG2b response to Cz. Sera from chronically T. cruzi -infected subjects with mild disease displayed higher levels of total IgG and IgG2 antibodies specific for sulfated epitopes compared with those in more severe forms of the disease. A significant reduction of C-T-specific delayed-type hypersensitivity reaction in C-T-immunized mice was observed when desulfated C-T was challenged, suggesting the involvement of sulfate groups in the generation of memory T-cell responses. Moreover, immunization with C-T in the absence of infection elicited ultrastructural abnormalities in heart tissue. Surprisingly, hearts from sulfate-depleted C-T-immunized mice did not present pathological alterations. This is the first report showing that sulfate-bearing glycoproteins from trypanosomatids are able to elicit specific humoral and cellular immune responses and appeared to be involved in the generation of heart tissue damage. These results represent a further step in the understanding of the role of Cz in the course of T. cruzi infection. © The Japanese Society for Immunology. 2008. All rights reserved.

Descripción: 1. 1. The reaction between 5,5′-dithio-bis-(2-nitrobenzoic acid) (DTNB) and the SH groups of soybean callus succinyl-CoA synthetase has been investigated. At pH 8-6 and 25° C, four SH groups are titrable with DTNB in the native enzyme. No additional thiol groups have been revealed after unfolding of the protein with 8 M urea. 2. 2. The loss of enzymatic activity paralleled the decrease in the number of free SH groups. As with p-mercuribenzoate and other mercurials, reaction with DTNB also resulted in dissociation of the enzyme into subunits. © 1974.

Descripción: Splitting and apparent splicing of ribosomal RNA, both previously unknown in vertebrates, were found in rodents of the genus Ctenomys. Instead of being formed by a single molecule of 4.4 kb, 28S rRNA is split in two molecules of 2.6 and 1.8 kb. A hidden break, mapping within a 106 bp 'intron' located in the D6 divergent region, is expressed in mature ribosomes of liver, lung, heart and spleen, as well as in primary fibroblast cultures. Testis-specific processing eliminates the intron and concomitantly the break site, producing non-split 28S rRNA molecules exclusively in this organ. The intron is flanked by two 9 bp direct repeats, revealing the acquisition by insertion of a novel rRNA processing strategy in the evolution of higher organisms.

Descripción: Galectins are a family of evolutionarily conserved animal lectins with pleiotropic functions and widespread distribution. Fifteen members have been identified in a wide variety of cells and tissues. Through recognition of cell surface glycoproteins and glycolipids, these endogenous lectins can trigger a cascade of intracellular signaling pathways capable of modulating cell differentiation, proliferation, survival, and migration. These cellular events are critical in a variety of biological processes including embryogenesis, angiogenesis, neurogenesis, and immunity and are substantially altered during tumorigenesis, neurodegeneration, and inflammation. In addition, galectins can modulate intracellular functions and this effect involves direct interactions with distinct signaling pathways. In this review, we discuss current knowledge on the intracellular signaling pathways triggered by this multifunctional family of β-galactoside-binding proteins in selected physiological and pathological settings. Understanding the "galectin signalosome" will be essential to delineate rational therapeutic strategies based on the specific control of galectin expression and function. © 2009 IUBMB.

Descripción: β-Lapachone, an o-naphthoquinone, induces a novel caspase- and p53-independent apoptotic pathway dependent on NAD (P) H:quinone oxidoreductase 1 (NQO1). NQO1 reduces β-lapachone to an unstable hydroquinone that rapidly undergoes a two-step oxidation back to the parent compound, perpetuating a futile redox cycle. A deficiency or inhibition of NQO1 rendered cells resistant to beta;-lapachone. Thus, β-lapachone has great potential for the treatment of specific cancers with elevated NQO1 levels (e.g., breast, non - small cell lung, pancreatic, colon, and prostate cancers). We report the development of mono(arylimino) derivatives of β-lapachone as potential prodrugs. These derivatives are relatively nontoxic and not substrates for NQO1 when initially diluted in water. In solution, however, they undergo hydrolytic conversion to β-lapachone at rates dependent on the electron-withdrawing strength of their substituent groups and pH of the diluent. NQO1 enzyme assays, UV-visible spectrophotometry, high-performance liquid chromatography-electrospray ionization-mass spectrometry, and nuclear magnetic resonance analyses confirmed and monitored conversion of each derivative to β-lapachone. Once converted, β-lapachone derivatives caused NQO1-dependent, μ-calpain-mediated cell death in human cancer cells identical to that caused by β-lapachone. Interestingly, coadministration of N-acetyt-L-cysteine prevented derivative-induced cytotoxicity but did not affect β-lapachone lethality. Nuclear magnetic resonance analyses indicated that prevention of β-lapachone derivative cytotoxicity was the result of direct modification of these derivatives by N-acetyl-L-cysteine, preventing their conversion to β-lapachone. The use of β-lapachone mono(arylimino) prodrug derivatives, or more specifically a derivative converted in a tumor-specific manner (i.e., in the acidic local environment of the tumor tissue), should reduce normal tissue toxicity while eliciting tumor-selective cell killing by NQO1 bioactivation. © 2005 American Association for Cancer Research.

Descripción: The insect tracheal system is a continuous tubular network that ramifies into progressively thinner branches to provide air directly to every organ and tissue throughout the body. During embryogenesis the basic architecture of the tracheal system develops in a stereotypical and genetically controlled manner. Later, in larval stages, the tracheal system becomes plastic, and adapts to particular oxygen needs of the different tissues of the body. Oxygen sensing is mediated by specific prolyl-4-hydroxylases that regulate protein stability of the alpha subunit of oxygen-responsive transcription factors from the HIF family. Tracheal cells are exquisitely sensitive to oxygen levels, modulating the expression of hypoxia-inducible proteins that mediate sprouting of tracheal branches in direction to oxygen-deprived tissues. © 2009 Elsevier Ltd. All rights reserved.

Descripción: Nasal secretions were studied in 80 allergic adults patients: 16 with intermittent rhinitis and 64 with persistent rhinitis. The percentage of supranuclear stria of ciliated cells with regard to leucocytes was studied by nasal scraping. Four groups of patients were classified according to nasal leucocytic predominance: patients with eosinophilic predominance with eosinophils > 10% in Group A (N=23), patients with abundant neutrophils and eosinophils > 10% in Group B (N=15), patients with scant leucocytes in Group C (N=29), patients with neutrophilic predominance without eosinophils in Group D (N=13). An increase of supranuclear stria percentage was correlated to eosinophils > 10% and also correlated to scant leucocytes. Nevertheless, a significant decrease of supranuclear stria percentage was observed in neutrophilic leukocytosis of bacterial etiology.

Descripción: The bcl-X gene plays a critical role in apoptosis. Six different isoforms generated by tissue-specific promoter usage and alternative splicing were described. Some of them exert opposite effects on cell death. In mammary epithelial cells glucocorticoids induce bcl-X expression and increase the ratio bcl-XL (antiapoptotic)/bcl-XS (apoptotic) by activating P4 promoter, which contains two hormone response elements. Here we show that, on mouse thymocytes and T lymphocyte derivative S49 cells, glucocorticoids inhibited transcription from P4 and decreased the ratio bcl-X L/bcl-XS favoring apoptosis. Upon hormonal treatment, glucocorticoid receptor (GR), steroid receptor coactivator-1, and RNA polymerase II were transiently recruited to P4 promoter, whereas STAT5B was also recruited but remained bound. Concomitant with the release of GR, silencing mediator for retinoic acid receptor and thyroid hormone receptor and histone deacetylase 3 were recruited, histone H3 was deacetylated, and RNA polymerase II left the promoter. Inhibition of STAT5 activity reverted glucocorticoid repression to activation of transcription and was accompanied by stable recruitment of GR and RNA polymerase II to P4. © 2006 by The American Society for Biochemistry and Molecular Biology, Inc.

Descripción: The molecular mechanisms governing the pathogenesis of ACTH-secreting pituitary adenomas are still obscure. Furthermore, the pharmacological treatment of these tumors is limited. In this study, we report that bone morphogenetic protein-4 (BMP-4) is expressed in the corticotrophs of human normal adenohypophysis and its expression is reduced in corticotrophinomas obtained from Cushing's patients compared with the normal pituitary. BMP-4 treatment of AtT-20 mouse corticotrophinoma cells has an inhibitory effect on ACTH secretion and cell proliferation. AtT-20 cells stably transfected with a dominant-negative form of the BMP-4 signal cotransducer Smad-4 or the BMP-4 inhibitor noggin have increased tumorigenicity in nude mice, showing that BMP-4 has an inhibitory role on corticotroph tumorigenesis in vivo. Because the activation of the retinoic acid receptor has an inhibitory action on Cushing's disease progression, we analyzed the putative interaction of these two pathways. Indeed, retinoic acid induces both BMP-4 transcription and expression and its antiproliferative action is blocked in Smad-4dn- and noggin-transfected Att-20 cells that do not respond to BMP-4. Therefore, retinoic acid induces BMP-4, which participates in the antiproliferative effects of retinoic acid. This new mechanism is a potential target for therapeutic approaches for Cushing's disease. Copyright © 2006 by The Endocrine Society.

Descripción: Gliomas are the most common primary brain tumors and yet almost incurable due mainly to their great invasion capability. This represents a challenge to present clinical oncology. Here, we introduce a mathematical model aiming to improve tumor spreading capability definition. The model consists in a time dependent reaction-diffusion equation in a three-dimensional spatial domain that distinguishes between different brain topological structures. The model uses a series of digitized images from brain slices covering the whole human brain. The Talairach atlas included in the model describes brain structures at different levels. Also, the inclusion of the Brodmann areas allows prediction of the brain functions affected during tumor evolution and the estimation of correlated symptoms. The model is solved numerically using patient-specific parametrization and finite differences. Simulations consider an initial state with cellular proliferation alone (benign tumor), and an advanced state when infiltration starts (malign tumor). Survival time is estimated on the basis of tumor size and location. The model is used to predict tumor evolution in two clinical cases. In the first case, predictions show that real infiltrative areas are underestimated by current diagnostic imaging. In the second case, tumor spreading predictions were shown to be more accurate than those derived from previous models in the literature. Our results suggest that the inclusion of differential migration in glioma growth models constitutes another step towards a better prediction of tumor infiltration at the moment of surgical or radiosurgical target definition. Also, the addition of physiological/psychological considerations to classical anatomical models will provide a better and integral understanding of the patient disease at the moment of deciding therapeutic options, taking into account not only survival but also life quality. © 2012 Suarez et al.

Descripción: To investigate the expression of leptin receptors (Ob-R) in the rat hypothalamus-pituitary-ovarian axis, immature rats were treated with eCG/ hCG and Ob-R expression was evaluated by western blot analysis. The Ob-R expression increased 24 h after eCG administration in all the tissues assayed. In the hypothalamus, these levels immediately decreased to those obtained without treatment. In the pituitary, the Ob-R expression continued to be elevated 48 h after eCG administration, whereas the hCG injection did not modify these levels. Similar results were obtained with the ovarian long isoform. To assess the effect of leptin on its receptors, Ob-R was assessed in hypothalamus, pituitary and ovarian explants cultured in the presence or absence of leptin (0.3-500 ng/ml). In the hypothalamus, we found a biphasic effect: the Ob-R expression was either reduced or increased at low or high concentrations of leptin respectively. LH-releasing hormone secretion increased at 1 ng/ml. In the pituitary, Ob-R increased at 10 or 30 ng/ml of leptin for the long and short isoforms respectively. Leptin also induced an increase in LH release at 30 ng/ml. In the ovarian culture, the presence of leptin produced an increase in Ob-R expression at different ranges of concentrations and a dose-dependent biphasic effect on the progesterone, production. In conclusion, all these results clearly suggest that leptin is able to modulate the expression of its own receptors in the reproductive axis in a differential way. Moreover, the positive or negative effect that leptin exerts on the ovulatory process may be dependent on this regulation. © 2008 Society for Endocrinology.