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M Rodriguez

Publications and source records attributed to M Rodriguez.

At least 343 records · Page 19Linked to original sources
PubMed1994

Peptide inhibitors of src SH3-SH2-phosphoprotein interactions.

Activated pp60c-src has been implicated in a number of human malignancies including colon carcinoma and breast adenocarcinoma. Association of the src SH2 domain with tyrosine-phosphorylated proteins plays a role in src-mediated signal transduction. Inhibitors of src SH2 domain-phosphoprotein interactions are, thus, of great interest in defining the role(s) of src in signal transduction pathways. To facilitate such studies, an enzyme-linked immunosorbent assay (ELISA) was developed to detect inhibitors of src SH2-phosphoprotein interactions. This assay measures inhibition of binding of a fusion construct (glutathione S-transferase src SH3-SH2) with autophosphorylated epidermal growth factor receptor tyrosine kinase domain. Activities of phosphopeptide segments derived from potential src SH2 cognate phosphoprotein partners were determined, with the focal adhesion kinase-derived segment VSETDDY*AEIIDE yielding the highest inhibitory activity. Structure activity studies starting from acetyl (Ac)-Y*EEIE have identified Ac-Y*Y*Y*IE as the most active compound screened in the ELISA. This compound is at least 20-fold more active than the parent peptide Ac-Y*EEIE. A high resolution (2 A) crystal structure of human src SH2 complexed with Ac-Y*EEIE was obtained and provided a useful framework for understanding the structure-activity relationships. Additionally, Ac-Y*EEIE was able to block interactions between src and its cellular phosphoprotein partners in vanadate-treated cell lysates from MDA-MB-468 breast carcinoma cells. However, it is unable to abrogate proliferation of MDA-MB-468 cells in culture, presumably because of poor cell penetration and/or lability of the phosphate group on tyrosine.

Amino Acid Sequence↗
PubMed1994

Aconitase is readily inactivated by peroxynitrite, but not by its precursor, nitric oxide.

Mitochondrial and cytosolic aconitases have been indicated as major targets of .NO- and O2-.-mediated toxicity in cells due to the oxidant-mediated disruption of the [4Fe-4S] prosthetic group. However, under circumstances in which both .NO and O2-. are generated, their almost diffusion-controlled combination reaction (k = 6.7 x 10(9) M-1 s-1), leading to the formation of peroxynitrite anion (ONOO-), can out-compete the direct reactions of .NO and O2-. with aconitase and even the enzymatic dismutation of O2-. by superoxide dismutase. In this work, we report that ONOO- reacts with isolated pig heart mitochondrial aconitase at 1.4 x 10(5) M-1 s-1, resulting in a significant loss of enzymatic activity. Aconitase activity was totally recovered after postincubation with thiols and ferrous iron, indicating that ONOO- reactions with the enzyme involve the perturbation of the labile Fe alpha to yield the inactive [3Fe-4S] cluster, which is also evident by spectral changes. On the other hand, anaerobic exposure of isolated aconitase to high concentrations of .NO (> 100 microM) led to a moderate inhibition of the enzyme, which could be fully overcome by .NO displacement under an argon-saturated atmosphere, in agreement with the formation of a reversible inhibitory complex between .NO and the active site of aconitase. Superoxide inactivated mitochondrial aconitase at (3.5 +/- 2) x 10(6) M-1 s-1, a reaction rate 3 orders of magnitude slower than its reaction rate with .NO. O2-. could represent the main mechanism of inactivation of the enzyme in systems in which it is formed without significant concomitant production of .NO. Our results imply that the mechanisms by which .NO and O2-. inactivate aconitase in cell systems may not be simple due to their direct reactions with the iron-sulfur cluster, but may rely on the formation of ONOO-.

Aconitate Hydratase↗
PubMed1994

Recombinant human IL-6 suppresses demyelination in a viral model of multiple sclerosis.

We used a murine model of multiple sclerosis (MS) induced by Theiler's murine encephalomyelitis virus (TMEV) to test the effect of IL-6 on central nervous system (CNS) demyelination. Administration of human rIL-6 (2.5 micrograms/dose), beginning one day before infection and then twice daily for 28 days, dramatically reduced demyelination and inflammation in the spinal cord of susceptible SJL/J mice. Benefit also was observed when rIL-6 was used as a therapeutic agent and begun on day 15 after infection, a time in which there is the first evidence of inflammation and demyelination in the spinal cord. Suppression of myelin damage by treatment with rIL-6 was associated with fewer virus Ag-positive cells in the spinal cord. Infectious CNS virus titers, as measured by plaque assay, were reduced in rIL-6-treated animals on day 15 after infection, but not on day 7, 22, or 29 after infection. Total serum Igs and virus-specific Igs, as detected by indirect ELISA, were increased markedly in rIL-6-treated mice, whereas no effect was observed on TMEV-neutralizing Ab titers. In vivo administration of rIL-6 inhibited a murine CNS-demyelinating disease induced by a virus, suggesting that this IL may have application for the treatment of human MS.

Animals↗
PubMed1994

Microglia in invertebrate ganglia.

The results of this study lend strong support to the concept of the existence in insects and molluscs of a distinctive class of neuroglial cells comparable to vertebrate microglia. The evidence presented is as valid as that used in reference to the separate status of vertebrate microglia--i.e., the demonstration of a close structural and functional relationship of these cells with cells of the immune system. As in vertebrates, the excision of ganglia from three invertebrate species (the molluscs Planorbarius corneus and Mytilus edulis and the insect Leucophaea maderae) and their maintenance in incubation media led to an exodus of small cells and their accumulation in the culture dish. During this process, they underwent conformational changes from stellate to rounded, and then to more or less ameboid, comparable to those indicative of the process of activation in the animals' immunocytes. Functional characteristics which these translocated microglia-like cells share with immunocytes are motility, phagocytotic activity, and adherence to the culture dish. Furthermore, the two cells have certain biochemical features in common--e.g., the presence of certain cytokines and (at least in Planorbarius) that of corticotropin. An additional phenomenon of particular interest for the classification of microglial elements is their response to morphine. At 10(-6) M, this drug decreases not only the number of cells emerging from the excised ganglia but also the degree of their transformation to the "active" ameboid form. This dose-dependent and naloxone-sensitive effect of morphine on microglial cells parallels that on activated immunocytes of the same species. Corresponding results demonstrating an inhibitory effect of morphine on mobilized microglial cells of the frog Rana pipiens indicate that this relationship between the two cell types under consideration also exists in vertebrates. Binding and displacement experiments with membrane homogenates of microglial cells as well as immunocytes of Mytilus have shown that the effects of morphine on both cell types are mediated by the same special opiate receptor (mu 3).

Animals↗
PubMed1994

Effects of gastrin on 3',5'-cyclic adenosine monophosphate, intracellular calcium, and phosphatidylinositol hydrolysis in human colon cancer cells.

Gastrin is a trophic factor for some human colon cancer cells. However, the signal-transduction pathways by which gastrin regulates growth are still unknown. We examined the effect of synthetic human gastrin-17 (G-17) on signal-transduction pathways and cell growth using 4 different human colon cancer cell lines (LoVo, COLO 320, HT-29, and HCT116). G-17 stimulated the production of cyclic AMP in LoVo, COLO 320, and HCT116 cells, while G-17 stimulated phosphatidylinositol hydrolysis and mobilization of intracellular calcium in HT-29 cells. The growth-regulatory effect of G-17 on these colon cancer cells (stimulatory on LoVo, COLO 320, and HT-29 cells; inhibitory on HCT116 cells) was well correlated with the effect of G-17 on the signal-transduction pathway in each cell line. We further examined the effect of a selective cholecystokinin-B type receptor antagonist, JMV 320, on G-17-induced signal-transduction pathways and G-17-regulated growth. In each cell line, the effect of JMV 320 on G-17-induced signal-transduction pathways was well correlated with that on G-17-regulated growth. G-17 appears to regulate, at least to some extent, growth of human colon cancer cells through gastrin receptor-linked signal-transduction pathways that are cell-specific.

Calcium↗
PubMed1994

National survey of ovarian carcinoma XII. Epithelial ovarian malignancies in women less than or equal to 25 years of age.

BACKGROUND: Epithelial ovarian carcinoma in women less than or equal to 25 years of age is a rare entity. This study used the database of the National Survey of Ovarian Carcinoma to analyze the disease and survival in women less than or equal to 25 years of age. METHODS: Tumor registries of 1230 hospitals were asked to enter the first 25 patients with histologically confirmed ovarian carcinoma from January 1 to December 31, 1983 and from January 1 to December 31, 1988. Data for a total of 12,136 patients were collected. Survival analysis and long-term evaluations were available on patients diagnosed with cancer in 1983. Chi-square analysis was used to compare the frequencies of operations performed in 1983 and 1988. RESULTS: Of 12,136 patients with epithelial ovarian carcinoma, 135 (1.1%) were less than or equal to 25 years of age. The majority of patients had early disease with the following distributions: stage I, 58.5%; stage II, 8.9%; stages III and IV, 28.9%. More patients had early-grade lesions with the following distributions: borderline, 21.5%; Grade 1, 27.4%; Grade 2, 11.1%; Grade 3, 6.7%; and unknown grade, 33.3%. Optimal cytoreduction was achieved in 77% of patients. During the 5-year study period, there was a significant change in the patterns of care toward more conservative surgery. In particular, unilateral salpingooophorectomy increased significantly from 38.2 to 59.7% (P = 0.0237), whereas hysterectomy decreased proportionally from 54.4 to 29.9% (P = 0.0039). The overall 5-year survival rate was 87.3% with the following divisions: stage I, 96.7%; stage II, 90.0%; stage III, 78.5%; and stage IV, 76.4%. Regarding histologic grade, 5-year survival rates were: borderline, 91.6%; Grade 1, 93.7%; Grade 2, 85.7%; Grade 3, 33.3%. CONCLUSION: Young patients with epithelial ovarian carcinoma appeared to have favorable stage and histologic grade. These factors combined with good performance status and optimal cytoreduction resulted in improved survival from cancer.

Adult↗
PubMed1994

[The value of silastic prostheses in Kienböck's disease].

Eight patients underwent silicon replacement arthroplasty for treatment of Kienböck's disease between 1980 and 1984. Seven patients were available for a clinical and radiological ten-year follow-up control. A three-stemmed arthrodesis by arthrosis was done on one patient. Subjective results were good, although a reduction of one third of the mobility and strength of the wrist was noticed. Erosive osteolysis, carpal instability, radiocarpal arthrosis and a 36% reduction of the initial height of the implants was seen on the X-rays. The lytic lesion represents a progressive silicone particle-wear synovitis which threatens the future of the carpus. Nowadays, this kind of arthroplasty no longer has its place in the treatment of Kienböck's disease.

Adolescent↗
PubMed1994

Involvement of pp60c-src with two major signaling pathways in human breast cancer.

The phosphotyrosine residues of receptor tyrosine kinases serve as unique binding sites for proteins involved in intracellular signaling, which contain SRC homology 2 (SH2) domains. Since overexpression or activation of the pp60c-src kinase has been reported in a number of human tumors, including primary human breast carcinomas, we examined the interactions of the SH2 and SH3 domains of human SRC with target proteins in human carcinoma cell lines. Glutathione S-transferase fusion proteins containing either the SH2, SH3, or the entire SH3/SH2 region of human SRC were used to affinity purify tyrosine-phosphorylated proteins from human breast carcinoma cell lines. We show here that in human breast carcinoma cell lines, the SRC SH2 domain binds to activated epidermal growth factor receptor (EGFR) and p185HER2/neu. SRC SH2 binding to EGFR was also observed in a nontumorigenic cell line after hormone stimulation. Endogenous pp60c-src was found to tightly associate with tyrosine-phosphorylated EGFR. Association of the SRC SH2 with the EGFR was blocked by tyrosyl phosphopeptides containing the sequences surrounding tyrosine-530, the regulatory site in the SRC C terminus, or sequences surrounding the major sites of autophosphorylation in the EGFR. These results raise the possibility that association of pp60c-src with these receptor tyrosine kinases is an integral part of the signaling events mediated by these receptors and may contribute to malignant transformation.

Amino Acid Sequence↗
PubMed1994

Calcitriol corrects deficient calcitonin secretion in the vitamin D-deficient elderly.

The thyroid calcitonin-producing C cells possess vitamin D receptors and synthesize the vitamin D-dependent calbindin D28K. The present study evaluates the possible direct or indirect influence of vitamin D on calcitonin secretion in the elderly. Serum calcitonin was measured before and after a short calcium infusion (1.5 mg/kg over 10 minutes) in nine normal young adults (30 +/- 4 years, mean +/- SEM) and eight elderly subjects (78 +/- 4 years). The test was repeated 48 h after the last of three intravenous injections of calcitriol (2 micrograms) given every other day. Basal serum calcium did not change, but basal calcitonin of the elderly increased from 7 +/- 1 to 10 +/- 1 pg/ml (p < 0.06), similar to basal values in young adults (11 +/- 1 pg/ml). The increase in calcitonin after calcium infusion increased from 8 +/- 1 to 14 +/- 1 pg/ml (p < 0.001) after calcitriol treatment and approached the increase in young adults (18 +/- 3 pg/ml). These data demonstrate that calcitriol can improve and nearly normalize the impaired calcitonin secretion of the mildly vitamin D-deficient elderly subjects without changes in serum calcium, whereas the inverse situation is observed for parathyroid hormone.

Adult↗
PubMed1994

Inhibition of mitochondrial electron transport by peroxynitrite.

Mammalian mitochondria are sensitive targets of the cytotoxic effects of superoxide (O.2-) and nitric oxide (.NO). In turn, when superoxide and nitric oxide are simultaneously produced, they rapidly react with each other yielding the highly oxidizing peroxynitrite anion (ONOO-) which may be also toxic to mammalian mitochondria. In this study we report that peroxynitrite exposure to rat heart mitochondria resulted in significant inactivation of electron carriers such as succinate dehydrogenase and NADH dehydrogenase as well as the mitochondrial ATPase. As a result of enzyme inactivation, peroxynitrite lead to a profound inhibition of glutamate/malate- and succinate-supported oxygen consumption but did not cause mitochondrial uncoupling. Secondary to inhibiting mitochondrial electron transport, peroxynitrite induced an enhanced succinate-stimulated hydrogen peroxide formation by heart mitochondria. Most of the damaging effects against mitochondria can be ascribed to peroxynitrite anion itself and not to hydroxyl radical-like oxidant yielded during the proton-catalyzed decomposition of peroxynitrite, as hydroxyl radical scavengers provided a rather modest protection. Our observations indicate that mitochondria may constitute a key intracellular loci for the toxic effects of peroxynitrite under the various pathological conditions in which peroxynitrite appears to play a contributory role.

Animals↗
PubMed1994

Analysis of sites of foot and mouth disease virus persistence in carrier cattle via the polymerase chain reaction.

This study was undertaken in order to explore possible sites of foot-and-mouth disease virus (FMDV) persistence during the carrier state. Tissue samples taken from experimentally infected animals at different times post-infection (p.i.) were examined by conventional viral isolation and the polymerase chain reaction (PCR) technique. The analysis of samples from several organs taken from 17 bovines between 3 and 270 days p.i. allowed the following conclusions: 1) Virus present in oesophageal-pharyngeal fluids (OPF) during the carrier state originates in the pharynx as shown by the detection of antisense FMDV RNA by PCR, 2) PCR is more sensitive than standard virus isolation techniques and may be used for the rapid detection of FMDV in specimens obtained during the acute stage of FMD and for identification of persistently infected cattle.

Animals↗
PubMed1994

Motor and somatosensory evoked potentials in mice infected with Theiler's murine encephalomyelitis virus.

We used an in vivo technique to record spinal motor and somatosensory evoked potentials in SJL/J and B10 mice chronically (4-10 months) infected with Daniel's strain of Theiler's murine encephalomyelitis virus (TMEV). SJL/J mice demonstrated primary spinal cord demyelination with chronic TMEV infection, whereas B10 mice were resistant to TMEV induced demyelination. Analysis based on the velocity of the initial peak of evoked responses demonstrated significantly slower conduction velocities in infected SJL/J mice as compared to age-matched uninfected SJL/J controls (p < 0.01) and infected B10 mice (p < 0.01). We noted no significant differences in conduction velocities of spinal evoked potentials recorded between uninfected SJL/J mice, uninfected B10 mice and infected B10 mice. Chronic infection with TMEV in susceptible SJL/J mice is associated with slowed conduction of spinal motor and somatosensory evoked potentials. This sensitive electrophysiologic assay will provide an in vivo method to test therapeutic regimens to inhibit demyelination or promote remyelination.

Animals↗
PubMed1994

Maternal ingestion of tyrosine during rat pregnancy modifies the offspring behavioral lateralization.

It was previously reported that oral administration of tyrosine (500 mg/kg) to pregnant rats increases tyrosine and monoamines level in the fetal brain and modifies locomotion during postnatal life. In the present study, it was found that this treatment alters behavioral lateralization in the offspring. Neonatal rats whose mothers received tyrosine during the second half of gestation showed a low level of absolute and population laterality in both tail and head movements. The alteration of behavioral lateralization was also found during postnatal development and during adulthood. The T-maze behavioral ontogeny was different for tyrosine-mother and sham-treated or untreated mother rats. During adulthood, the T-max lateralization after stress sessions (a procedure that decreases alternation behavior and facilitates the quantification of behavioral lateralization) was also different in control and tyrosine-mother groups. Neonatal and adult rats showed an increase in right-side movements probability. These data provide evidence that maternal ingestion of a catecholamine precursor during gestation may induce a long-lasting modification of the behavioral lateralization of the offspring.

Administration, Oral↗
PubMed1994

Permanent dopaminergic alterations in the n. accumbens after prenatal stress.

It has been suggested that stress during the initial stages of human life may serve as a predisposing factor to mental illness. Recently, we reported that in pregnant rats, stress induces an increase of behavioral depression in the female offsprings when adult. This article describes the effect of prenatal stress on central dopaminergic transmission during adulthood. The offspring of stressed mothers showed an increase of behavioral depression in the Porsolt test and a reduction of DOPAC, HVA, and DOPAC/DA index in the n. accumbens. The effect on the right accumbens was more marked than on the left. A great body of information exists to suggest that depression is related to a decrease of dopaminergic neurotransmission, and the present data provide new evidence in support of the hypothesis that maternal stress during gestation increases the risk of depression in the offspring. We are also reporting a hitherto uncommented relationship between behavioral depression in the Porsolt test and the decrease of dopamine transmission in the n. accumbens.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

Ontogenic development of brain asymmetry in dopaminergic neurons.

In the present study the right-left brain asymmetry of central dopamine (DA) systems during postnatal brain development is evaluated. DA and dihydroxyphenylacetic acid (DOPAC) levels increased from neonatal to adult life in both the forebrain and mesencephalon. This increase was not similar in the right and left brain sides. From neonatal life to adulthood a fall was observed in (a) DA percentage in the DA high-brain side in the mesencephalon and (b) DOPAC percentage in the DOPAC high-brain side in both the forebrain and mesencephalon. The percentage of lateralized rats (more than 65% of DA or DOPAC levels in either brain side) also decreased during ontogeny. Thus, biochemical lateralization decreases during ontogeny. The right-left brain correlation for DA level and DA turnover was used to evaluate the inter-hemispheric regulation of dopaminergic systems. The correlation coefficient was near to 0 during postnatal life and around -0.8 during adulthood in both forebrain and mesencephalon. Taken together, these data suggest that the ontogenic decrease of in brain asymmetry for DA or DOPAC levels is related to the postnatal development of an inter-hemispheric regulatory system that control dopaminergic neurons activity.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

Immune promotion of central nervous system remyelination.

Remyelination by oligodendrocytes is the normal response to injury of the central nervous system following experimental demyelination by toxins and viruses in rodents. By contrast, in immune-mediated myelin disorders such as human MS, Theiler's virus-induced demyelination or EAE, remyelination is incomplete. We have considered two hypotheses to explain why myelin repair is incomplete in these disorders. Hypothesis I is that myelin repair is the normal consequence of primary myelin injury but there are immune factors which prevent its full expression. To test hypothesis I, we depleted T cells in Theiler's virus infected mice with cyclophosphamide or with monoclonal antibodies to CD4, CD8, or immune response gene products (Ia). Enhanced remyelination and proliferation of glial cells was observed in mice depleted of CD4+ or CD8+ T cells. Hypothesis II is that there are immune factors within some demyelinated lesions which, when present, promote new myelin synthesis. We envision these factors to be present in those lesions showing remyelination but absent in those lesions that remain demyelinated. To test hypothesis II, we generated polyclonal immunoglobulins directed against normal CNS antigens. Transfer of immunoglobulins from mice immunized repeatedly with spinal cord homogenate resulted in 4-5-fold enhancement of remyelination in Theiler's virus infected mice. We have also generated a series of monoclonal antibodies directed against normal autoantigens which also promote CNS remyelination. These experiments support the concept that full CNS remyelination is possible in human demyelinating diseases such as MS. Manipulation of the immune response either by inhibiting the function of T cells or by treatment with immunoglobulins (possibly normal autoantibodies) appears to promote remyelination. These experiments provide hope for patients with fixed neurological deficits for whom there are currently no available therapies.

Adjuvants, Immunologic↗