Lack of accommodation after long-term survival of hamster xenografts in rats.
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Animals↗
Biomedical subjects
A Vidal
Publications and source records attributed to A Vidal.
Inhaled dopamine induces bronchodilatation in patients with bronchial asthma.
OBJECTIVE: To determine the probable bronchodilating effect of dopamine administered by inhalation route in patients with crisis of bronchial asthma and the effect of dopamine on bronchial motor tone. DESIGN AND METHOD: We have studied eighteen (18) patients with crisis of bronchial asthma, ten (10) subjects with bronchial hyperreactivity and ten (10) healthy subjects. Patients with other pulmonary or cardiac disease were excluded. All received by inhalation placebo (0.9% saline solution), dopamine at 0.5 microg/kg/min (controlled by heart rate and arterial pressure with a dynamap), and placebo. Respiratory parameters: forced vital capacity (FVC), forced expiratory volume at the first second (FEV1), forced maximal expiratory flow (FEFmax) and forced expiratory flow at the 50% of vital capacity (FEF50) were measured in each protocol period. Student's paired t test, Wilcoxon and Mann Whitney analysis were performed. RESULTS: After dopamine inhalation, there was an increase of FVC by 23% (p<0.001); an increase of FEV1 by 39% (p<0.0001); an increase of FEF50 by 33% (p<0.001) and an increase of FEFmax by 31% (p<0.001). There were no respiratory parameter changes in both, subjects with bronchial hyperreactivity and normal after dopamine inhalation. CONCLUSIONS: Inhaled dopamine induces bronchodilatation in patients with crisis of bronchial asthma. Inhaled dopamine neither alters basal bronchial tone in healthy subjects nor in subjects with bronchial hyperreactivity.
Administration, Inhalation↗
Overexpression of prothymosin alpha accelerates proliferation and retards differentiation in HL-60 cells.
Prothymosin alpha (ProTalpha) is an acidic nuclear protein the expression of which is related to the proliferation and differentiation processes in mammalian cells. In the present study we have stably transfected HL-60 cells, a biological system that allows the study of both proliferation and differentiation, with recombinant vectors encoding sense and antisense ProTalpha mRNA. In the HL-60 cell clones overexpressing ProTalpha we observed an acceleration in the growth rate, whereas expression of the antisense orientation showed the opposite effect. Moreover, cell-cycle analysis demonstrated that the G1-phase was shortened in the cells expressing the sense construct. Before studying how ProTalpha affects differentiation, we showed that the down-regulation of ProTalpha gene during differentiation occurs in all mammalian cell lines (HL-60, K562, U937, MEL C88, N2A and PC12) analysed. The biological effect evoked by the induction of the ProTalpha sense vector was the retardation of cell differentiation, although expression of the antisense construct showed no effect on differentiation. In conclusion, our findings provide evidence that ProTalpha is directly implicated in cellular proliferation and that the maintenance of high levels of ProTalpha inside HL-60 cells is incompatible with their ability to differentiate.
Cell Differentiation↗
Prothymosin alpha stimulates Ca2+-dependent phosphorylation of elongation factor 2 in cellular extracts.
Prothymosin alpha (PTA) stimulates in a dose-dependent manner the phosphorylation of a 105-kDa protein (p105) in cell extracts from different cell types. Protein sequencing and immunological analysis indicated that this protein is elongation factor 2 (EF-2). We propose that calcium/calmodulin-dependent protein kinase III is responsible for the PTA-dependent EF-2 phosphorylation based on the following lines of evidence: (a) Ca2+ is required for the effect; (b) calmodulin enhances the reaction, and calmodulin inhibitors block the phosphorylation; and (c) no phosphorylation is seen in cell extracts depleted of calmodulin-binding proteins. To obtain a strong phosphorylated EF-2 band, we found it necessary to add PTA to cytosolic extracts from synchronized dividing cells in various phases of the cell cycle except in mitosis. Since PTA is a nuclear protein everywhere in the cell cycle except in mitosis, when it is found in the cytoplasm, we hypothesize that, if PTA activates EF-2 phosphorylation in vivo, as present data suggest, its presence in the cytoplasm during mitosis could explain why EF-2 phosphorylation is mainly restricted to that phase of the cell cycle. Moreover, other bands in addition to EF-2 were phosphorylated in a calmodulin- and PTA-dependent manner, and several of them (in a range between 50 and 60 kDa) have similar Mr to those that conform to the holoenzyme calcium/calmodulin dependent protein kinase II, suggesting that PTA could have a more general function modulating the activity of various Ca2+/CaM-dependent enzymes along the cell cycle.
3T3 Cells↗
Developments in solar photocatalysis for water purification.
Photocatalytic processes in the presence of titanium dioxide provide an interesting route to destroy hazardous organic contaminants, being operational in the UV-A domain with a potential use of solar radiation. In this paper, some specific contaminant classes of interest such as ethylbenzene, gamma-lindane and EPTC have been tested at laboratory scale and in the field to determine the feasibility of the photocatalytic oxidation of organic contaminants in water. Our preliminary results at laboratory scale with these chemicals have provided a better understanding of the photocatalytic process which seems to be efficient and not selective. The application of these processes in removal of gamma-lindane from water operating in a parabolic trough concentrator has demonstrated to be effective, being possible to reduce 99.9% of gamma-lindane levels in water in acceptable times.
Benzene Derivatives↗
TGF-beta1 actions on FRTL-5 cells provide a model for the physiological regulation of thyroid growth.
Little is known about the TGF-beta1 mechanism that promotes thyroid cell growth arrest. We assessed TGF-beta1 effects on Fisher rat thyroid cell line (FRTL-5). This allowed us to study TGF-beta1 action on thyroid cells in various physiological situations such as actively proliferating cells, resting cells stimulated to proliferate by the action of various mitogens, and resting cells. TGF-beta1 arrested proliferating FRTL-5 cells, increasing c-myc mRNA levels and reducing p27-free cyclin D1 protein levels, without affecting either the cellular content of p27 or the cyclin D1-p27 complexes. Moreover, TGF-beta1 treatment reduced the activity of cyclin E-CDK2 complexes and, consequently, pRB was found to be hypophosphorylated. TGF-beta1 prevented resting cells to enter in the cell cycle when stimulated with growing medium (newborn calf serum plus a mixture of five hormones) but not when TSH (thyroid stimulating hormone) plus IGF-1 (Insulin-like growth factor I) were used as mitogens. Both stimuli increased the levels of cyclins D1, D3 and E but TGF-beta1 had a greater effect in decreasing these cyclin levels in growing-medium stimulated cells than in TSH + IGF-1. This suggests that for FRTL-5 cells, the content of these cyclins must exceed a threshold to progress through the cell cycle. TGF-beta1 induced apoptosis in quiescent cells, accompanied by a reduction in p27 protein levels and an increase in c-myc expression. Interestingly, TGF-beta1-induced variations in prothymosin alpha and c-myc mRNA levels were not correlated. TGF-beta1 always promoted an increase of p15 mRNA levels. In summary, our results point to the fact that TGF-beta1 could play a physiological role in the control of thyroid growth through the modification of cell cycle regulatory proteins.
Animals↗
DNA sequence analysis of spontaneous lacI-d mutations in O6-alkylguanine-DNA alkyltransferase-proficient and -deficient Escherichia coli.
Spontaneous mutagenesis in O6-alkylguanine-DNA alkyltransferase-proficient and -deficient (ada ogt mutants) Escherichia coli was studied in two ways: in bacteria growing in nonselective liquid medium and in bacteria resting on selective agar plates. ATase mutants showed similar spontaneous mutation rates as ATase proficient bacteria during growth phase; an excess of mutants arising in nondividing cells. The resting-associated mutagenesis in ada + ogt + uvr- bacteria was biphasic; the high sensitive range being triggered beyond the first 6 days after plating. Contrarily, spontaneous Lacc mutants from ada- ogt- uvr- cells steadily increased over the 8 day period of plate incubation. These results suggested that, in the absence of nucleotide excision repair, the repair by both the Ada and the Ogt ATases is not saturated until the cells have been resting for 6 days. The spontaneous LacI-d mutation spectrum of ada + ogt + uvr- bacteria growing in non-selective liquid medium served as a baseline to determine the mutation events increased in the ATase-deficient derivative upon prolonged incubation on selective plates. The percentage of G:C-->A:T transitions, presumably driven by unrepaired O6-alkylguanine lesions, was increased at the expense of other mutation types. G:C-->A:T transitions accumulated with a pronounced 5'PuG bias, suggesting that the endogenous metabolite(s) responsible for this mutation class is an SN1 type alkylating compound(s). Accordingly, the site distribution of G:C-->A:T transitions in nondividing ATase defective bacteria showed similarities with the spectra induced by alkylnitrosoureas, particularly with those generating bulky alkylated DNA adducts.
Bacterial Proteins↗
Preparation of Magnetic Inks: Adsorption of Macromolecular Dispersion Agents on Magnetic Metallic Iron Pigments and Electrical Charge Formation
The interaction between metallic iron pigments (MPs) and the actual constituents of magnetic ink is examined by first determining the adsorption isotherms and analyzing by FTIR the type of bonding that is established between the constituents and MP. Then, following the approach described in a previous paper using model compounds, the formation of electrical charges on MPs is examined through acoustophorometric (Electrokinetic amplitude or ESA) measurements. It is shown that the variation in ESA is related to charge transfer processes and reflects the MP-constituent interactions. Finally, adsorption competitions are shown and the importance of the method of preparation (order of mixing of the ingredients of the ink) is illustrated. Copyright 1997 Academic Press. Copyright 1997Academic Press
Journal Article↗
[Chronic epigastric pain in an 18-year-old male].
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Abdominal Pain↗
Adsorption of Stearic Acid and Diethylhexyl Phosphate on Magnetic Metallic Iron Pigments: Electrical Surface Charging and Adsorption Competition
The adsorption of stearic acid and bis(2-ethylhexyl) phosphate, from toluene and THF solutions, on magnetic iron pigments (MP) was examined. Adsorption isotherms as well as the concomitant variations of surface electrical (zeta) potential were determined. The formation of electrical surface charges is explained by charge transfer processes between the solvents, the adsorbates, and MP. An adsorption competition is evidenced when contacting MP with the adsorbates using 14C-labeled stearic acid.
Journal Article↗
Long-term follow-up of Lambert-Eaton syndrome treated with intravenous immunoglobulin.
Recent reports have shown that patients with Lambert-Eaton myasthenic syndrome (LEMS) improve transiently after high-dose intravenous immunoglobulin (IVIG) administration. Information about the usefulness of IVIG for long-term treatment is rather scanty. Our findings demonstrate the efficacy of monthly IVIG courses at a dose of 0.4 g/kg/day for 5 days, in a 41-year-old patient with LEMS without detectable malignancy. Improvement in limb strength, peak expiratory flow rate, and electrophysiological parameters, as well as clinical signs following IVIG, was evident as early as 7 days after the first course and is still maintained at 24-months follow-up.
Adult↗
The influence of DNA repair by Ogt alkyltransferase on the distribution of alkylnitrosourea-induced mutations in Escherichia coli.
To determine the influence of DNA repair by Ogt alkyltransferase on the distribution of alkylnitrosourea-induced mutations, we have analysed in Ogt-proficient and Ogt-deficient bacterial strains the DNA sequence changes of a total of 357 independent mutations occurring within the initial part of the lacl gene of Escherichia coli. The majority (>80%) of mutations induced by either N-ethyl-N nitrosourea (ENU) or N-methyl-N-nitrosourea (MNU) in the two genetic backgrounds were G:C --> A:T transitions, consistent with the predominant role of the O6-alkylguanine miscoding lesion in mutagenesis by alkylating agents. The analysis of the distribution of G:C --> A:T transitions induced by ENU in Ogt+ and Ogt bacteria reveals an influence of the 5'-flanking base at the level of repair by Ogt alkyltransferase. The Ogt protein appears more efficient at repairing O6-ethylguanine lesions, which are flanked 5' by a G or C, in agreement with previously reported data from our group for ethylmethane sulfonate. In contrast, no preference could be inferred for the repair of O6-methylguanine lesions by Ogt protein. These results seem to indicate that the preference of the Ogt alkyltransferase to repair certain DNA sequences might be a function of the size of the alkyl group. The importance of the alkyl group length has been described also at the level of the (A)BC excinuclease machinery that seems to have a DNA sequence specificity opposite to that of Ogt alkyltransferose.
Base Sequence↗
Co-distribution of tropomyosin and alpha-actinin with actin in Psammobatis extenta electrocytes brings out their similarity with muscle fiber cytoplasm.
Electric organs of Psammobatis extenta (Rajiformes) electric fish derive from myoblasts of the caudal region (16). Here we study the presence of muscle proteins, actin and the actin-binding proteins, alpha-actinin and tropomyosin, in the electrocytes by means of biochemical approaches, scanning electron microscopy and immunocytochemical methods. NBD-phallacidin is employed to detect the filamentous form of actin (F-actin). Immunoblots of actin and alpha-actinin from P. extenta skeletal and smooth muscle show that the electric organ forms of actin and alpha-actinin correspond to muscle types. Scanning electron microscopy shows that P. extenta electrocytes are highly polarized cells, semicircular in shape, with an anterior, concave innervated face and a posterior, convex, non-innervated face. The immunofluorescence patterns of alpha-actinin and tropomyosin distribution are similar to those of actin, in that these epitopes appear to occur throughout the entire electrocyte cytoplasm. F-actin, as revealed by NBD-phallacidin fluorescence, was also found throughout the cytoplasm. This is the first time that evidence is presented to demonstrate the existence of muscle actin in this weak electric fish species electrocyte. The close evolutionary connection to that of muscle cells is discussed.
Actinin↗
Angiogenesis and malignant melanoma. Angiogenesis is related to the development of vertical (tumorigenic) growth phase.
To study angiogenesis in early steps of melanoma progression, 113 cutaneous melanomas 1 mm or less in thickness were stained with Ulex europaeus lectin. Vascular density was determined in the areas of greatest vascularization. To avoid the effect of anatomic location, the quotient between vascular density at the tumor base and in normal skin (vascular ratio) was obtained in each case. Of these melanomas, 46 were immunohistochemically stained for the presence of vascular endothelial growth factor (VEGF). Positivity was scored from 1-4 by comparing staining of melanoma cells with keratinocytes. Vascular ratio values in vertical growth phase melanomas were higher than those in radial growth phase when counting per 200 or 400 magnification (2.29 +/- 1.3 and 2.48 +/- 1.5 for vertical growth phase and 1.34 +/- 0.62 and 1.41 +/- 0.83 for radial growth phase melanomas, respectively). This difference was statistically significant (p < 0.0001 and p < 0.001 at x200 and x400, respectively). Also, VEGF staining was stronger in vertical growth phase melanomas when compared with radial growth phase melanomas (Chi square, p < 0.025). In conclusion, our findings suggest that angiogenesis and VEGF expression are associated with the development of vertical growth phase.
Cell Transformation, Neoplastic↗
Development of ELISA to estimate thymosin alpha1, the N terminus of prothymosin alpha, in human tumors.
We reported that tumor content of prothymosin alpha (ProT alpha) is a proliferation index of human breast tumors that might be used to identify patients at high risk for distant metastasis (Dominguez et al., Eur J Cancer 1993; 29A:893-7). In that study ProT alpha concentrations were measured by a RIA; here we present an alternative nonisotopic assay that could be used in a standard clinical laboratory. Main features of the ELISA are: (a) A recombinant fusion protein glutathione S-transferase (GST)-human ProT alpha was used to coat the microtiter plates; (b) we used a polyclonal antiserum raised in rabbits that detects thymosin alpha1, the NH2-terminal fragment of ProT alpha; (c) it is as sensitive as the RIA; (d) it is faster than the RIA. ProT alpha concentrations in various human tumors (skin, esophagus, colorectal, and breast) as assessed by ELISA were comparable with, although twofold greater than, the values previously estimated by RIA.
Antibody Specificity↗
Expression of the human growth hormone normal gene (hGH-N) in proliferating and differentiated HL-60 cells.
The possibility that human leukemic cells could synthesize growth hormone (GH) was investigated in the HL-60 cell line. Western blot analysis of protein extracts obtained from these cells revealed the existence of a major immunoreactive GH (irGH) band, with an approximate molecular weight of 22 kDa, together with lower amounts of 20- and 44-kDa bands. Stimulating proliferating HL-60 cells with KCl clearly increased GH concentration in the incubation medium as compared to basal values. RT-PCR amplification of HL-60 RNA and restriction assay of the amplimers demonstrated that those proteins were the result of the expression of the GH-N (normal) gene in this cell line. These results were confirmed by Northern blot, which also showed that the rate of GH-N gene expression was clearly dependent upon the proliferative state of the cells: while GH transcripts were easily detectable in actively proliferating cells, only minute amounts were observed when cells were induced to differentiate with dimethyl sulphoxide (DMSO). Similar differences were observed by Western blot. In all, these findings demonstrate that HL-60 cells are capable to produce and secrete a GH identical to pituitary GH. Interestingly, the rate of synthesis of the hormone dramatically increases when cells are actively proliferating. Therefore, it is likely that locally produced GH might be involved in the control of leukemic cell proliferation. Further studies are now in course to establish whether this mechanism occurs via an autocrine and/or paracrine way.
Base Sequence↗
Grain size effect on trace metals distribution in sediments from two coastal areas of Chile.
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Analysis of Variance↗
Vascular density and survival in cutaneous melanoma.
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Follow-Up Studies↗