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R García-Cañero

Publications and source records attributed to R García-Cañero.

12 recordsLinked to original sources
PubMed1999

Na+ :H+ exchange inhibition induces intracellular acidosis and differentially impairs cell growth and viability of human and rat hepatocarcinoma cells.

Amiloride and its more potent analog, hexamethylene amiloride (HMA), inhibits Na+ :H+ exchange and decreases intracellular pH in a concentration-dependent way in two human hepatocarcinoma cell lines and in a rat hepatocarcinoma cell line that differs in its phenotypic characteristics, resembling the clinical situation encountered in human hepatocarcinomas. After 24 h of exposure, DNA synthesis and cell protein content of the cultures decreases according to the concentration of the drugs and in parallel to Na+ exchange inhibition and the drop in pHi promoted. RNA and protein syntheses are less sensitive to its action. The above effects induced by HMA are accompanied by an abrupt decrease in cell viability and lysosomal integrity at 24 h. These effects develop gradually with the exposure time as does the increase in free radical production. Decreased viability is totally or partially restored by N-acetylcysteine or deferoxamine, but the degree of intracellular acidification produced is not. These results tend to suggest that intracellular acidification can diminish cell growth and provoke cytotoxic cell death by diminishing reduced glutathione (GSH) levels and impairing lysosomal integrity, reflecting the sensitivity of hepatocarcinoma cells to Na+ exchange inhibition and intracellular acidosis.

Acidosis↗
PubMed1999

Improvement in liver fibrosis, functionality and hemodynamics in CCI4-cirrhotic rats after injection of the Liver Growth Factor.

BACKGROUND/AIMS: Most substances used in experimental models of cirrhosis are chosen either as protectors of lipid peroxidation, as antifibrogenic agents or as vitamins, among others. In this report, we analyze the improvement produced, in established cirrhosis (CCl4 plus phenobarbital) in rats, by intraperitoneal injection of Liver Growth Factor, a hepatic mitogen with activity both in vivo and in vitro. METHODS: Following confirmation of CCl4-induced cirrhosis, Liver Growth Factor (4.5 microg per ratx2 injections/week for 3 weeks) was administered to one group of rats (Cirr+LGF). The remaining rats (Cirr) received saline. The groups were compared in terms of serum enzymes, tissue damage, total liver collagen, collagenase activity, microsomal enzyme activities, splanchnic and systemic hemodynamics and portosystemic shunting. RESULTS: Treatment of rats presenting CCl4-induced cirrhosis with Liver Growth Factor decreased serum aminotransferase levels and increased levels of serum albumin and total protein. The Liver collagen content was lower in rats treated with Liver Growth Factor (2.96 vs. 4.32 mg/g liver, p<0.01). Microscopic studies revealed that the livers of rats receiving Liver Growth Factor showed decreases in fibrosis, necrosis and inflammatory infiltration, as well as a recovery of architectural integrity. Liver function was improved after treatment with Liver Growth Factor, as indicated by the rate constant for elimination of aminopyrine, which increased from 0.0063 to 0.0170 (p<0.05). This increase was accompanied by a higher total amount of cytochrome P-450 as well as of certain P-450 isoenzymes, especially those that are hormone-dependent, such as P-450 3A. The improved liver histology and function observed in Cirr+LGF rats was associated with decreases in portal pressure (14.4 vs. 9.4 mm Hg, p<0.01) and portosystemic shunting (55.8 vs. 11.5%, p<0.01), as well as increases in mean arterial pressure and systemic vascular resistance, and a reduction in ascites. CONCLUSIONS: Administration of the hepatic mitogen, Liver Growth Factor, to CCl4-cirrhotic rats decreased liver collagen and reorganized the hepatic extracellular matrix, resulting in an improvement in liver function, reduced portal pressure and amelioration of ascites.

Aminopyrine↗
PubMed1994

Hepatic growth induced by injection of the liver growth factor into normal rats.

Normal Wistar rats injected with the liver growth factor (LGF), a mitogen specific for liver cells, experienced hepatic growth. LGF shows two peaks of activity in vivo, both of them mitogenic. Rats injected either with 6.8 ng or 3.9 micrograms LGF/rat every 3-4 days experienced liver growth showing a see-saw profile. Dry liver weight usually peaked at day 2 (microgram doses) or at day 3 (ng doses) after each injection, with increases of about 30% over controls. Liver DNA synthesis, measured by [3H]-thymidine incorporation, peaked 24 h after LGF injection at both doses. Liver protein synthesis, measured by [14]C-leucine incorporation, usually peaked 24 h after DNA synthesis maximums. Mitogen-stimulated cells were also assessed by immunohistochemical staining for proliferating cell nuclear antigen in livers of LGF-injected rats. Rats injected with rat serum albumin purified from normal rats to serve as controls showed a 6% increase in dry liver weight, but when serum albumin from 3-day fasted rats was injected instead, the increase was not statistically significant. The mild effect of rat serum albumin could be due to the lipid content of the solutions injected, but the level of lipids/mg protein in LGF solutions was half that determined with serum albumin from 3-day fasted rats. From the microscopic and ultramicroscopic studies carried out in rat livers injected with LGF at each dose, we observed: (1) an increase in the number of hepatocytes undergoing mitosis; (2) transient increases in lipid and glycogen contents, as occur after liver resection; (3) no signs of degeneration, such as the appearance of amyloids or fibrosis; (4) no increase in lysosome number, as in hepatotoxicity; (5) no alterations in endothelial or Kupffer cells; and (6) no ultrastructural signs of degeneration either in cytoplasmic organelles (rough endoplasmic reticulum, mitochondria) or in nuclei. One year after LGF injection, rat liver, pancreas, kidneys and spleen were normal, with no signs of degeneration or onset of fibrosis.

Animals↗
PubMed1991

Co-purification of calcium transport-stimulating and DNA synthesis-stimulating agents with parathormone-like activity isolated from the hypercalcaemic strain of the Walker 256 tumour.

One of the strains of the Walker 256 carcinosarcoma induces in the rat a humoral hypercalcaemia of malignancy (HHM) syndrome which is similar to that reported in human patients. We have isolated from this tumour a chromatographic fraction which displays an adenylate cyclase stimulating activity in dog kidney cortical membranes, similar to that of a parathormone (PTH) related protein isolated from various HHM related tumours. In addition, this fraction stimulated initial calcium (Ca) uptake in confluent Madin-Darby canine kidney (MDCK) cell monolayers in a dose-dependent manner. Maximal stimulation of Ca uptake was associated with an enhanced Ca efflux from MDCK cells preloaded with the cation, and with an increased DNA synthesis in these cells. These activities might be involved in development of increased tubular calcium reabsorption in Walker 256 tumour-bearing rats.

Adenylyl Cyclases↗
PubMed1989

Partial purification and characterisation of a renal growth factor from plasma of uninephrectomised rats.

Renal growth factor activity was extracted from plasma of adult uninephrectomised rats and partially purified by gel filtration and anion-exchanger FPLC. It induced a maximal stimulation of mouse DNA synthesis in vivo at 1.75 micrograms/mouse. In addition, renal growth factor was found to maximally stimulate DNA synthesis in LLC-PK1 cells at 150 ng/ml. This maximal response was then found to decrease with higher doses of renal growth factor, in vivo and in vitro. The apparent molecular weight of renal growth factor was estimated to be 17K-22 K by gel filtration. It was found to be resistant to heat and to trypsin, but labile to reduction with dithiothreitol.

Animals↗
PubMed1989

Liver growth factor purified from human plasma is an albumin-bilirubin complex.

We have reported that a liver growth factor isolated from plasma of partially hepatectomized rats is an albumin-bilirubin complex. In this paper, we characterize the liver growth factor purified from subjects with hepatitis (h-LGF). This factor increases synthesis of DNA in a dose-dependent manner both in vivo in mouse hepatocytes, with a dose of maximal stimulation of 150 ng of h-LGF/mouse, and in vitro in rat liver cell culture, with maximal effect at 7.5 to 10 ng of h-LGF/ml. In vivo, h-LGF increases the mitotic index of mouse hepatocytes, its action being organ-specific, acting on liver, but not on spleen, kidney, lung or brain. In vitro, h-LGF stimulates the uptake of 22Na+ by hepatocytes. In addition, we carried out a study comparing it with human serum albumin in terms of absorbance, fluorescence, circular dichroism spectra, amino acid composition, tryptic maps and antigenic determinants (Ouchterlony immunodiffusion). All these tests suggested that human serum albumin is a constituent of h-LGF. Moreover, when albumin isolated from humans without hepatic pathology is incubated with bilirubin, the albumin-bilirubin complex formed mimics the activity of the human liver growth factor with respect to stimulation of DNA synthesis and the effects on the mitotic index of mouse hepatocytes in vivo. We propose that this human liver growth factor is an albumin-bilirubin complex.

Amino Acids↗
PubMed1987

Identification of a liver growth factor as an albumin-bilirubin complex.

We have reported the purification and characterization of a protein that behaves as a liver growth factor, showing activity either in vivo or in vitro [Díaz-Gil et al. (1986) Biochem. J. 235, 49-55]. In the present paper, we identify this liver growth factor (LGF) as an albumin-bilirubin complex. This conclusion is supported by the results of chemical and spectroscopic characterization of this protein as well as by experiments in vivo. Incubation of albumin isolated from normal rats with bilirubin/albumin molar ratios (r) resulted (when r = 1 or 2) in a complex with liver DNA synthesis promoter activity identical with that of LGF. The exact amount of bilirubin bound to albumin was assessed by fluorescence and c.d. spectra. This albumin-bilirubin complex showed the same dose-dependence profile as LGF either at low or high dose of protein injected per mouse. Both LGF and albumin-bilirubin complex produced similar increases in the mitotic index of mouse hepatocytes in vivo. A new mechanism for the onset of the hepatic regenerative process is proposed.

Animals↗
PubMed1986

Purification of a liver DNA-synthesis promoter from plasma of partially hepatectomized rats.

A protein was isolated from plasma of partially (70%) hepatectomized rats that, injected in mice, increases the uptake of [3H]thymidine by liver DNA by 200-300% over that by injected control saline. The purification procedure consists essentially of three chromatography steps, employing Sephadex G-75, DEAE-cellulose and hydroxyapatite. The hepatic promoter (HP) preparation shows a single band in SDS/polyacrylamide (15%)-gel electrophoresis (silver stained), with an Mr of 64 000; its activity is suppressed by trypsin or pepsin and is unaffected by deoxyribonuclease or ribonuclease. On injection into mice (150 ng/mouse), it increases the mitotic index of the liver. It shows organ-specificity, acting on liver but not on spleen, kidney, lung or brain. In primary liver cultures, it produces an increase in uptake of [3H]thymidine into DNA in the range 1-10 ng/ml. In this system in vitro, it increases the uptake of 22Na+ immediately after addition.

Animals↗
PubMed1976

Effects and specificity of anticancer agents on the respiration and energy metabolism of tumor cells.

Using 35 new anticancer agents from the screening program of the National Cancer Institute we have performed a biochemical study of the effects on the respiration and oxidative phosphorylation of rat liver mitochondria and on the respiration of leukocyte, liver, L1210 leukemia, and Ehrlich ascites cell suspensions. Fifteen of the 35 compounds were found to be potent respiratory inhibitors as defined by 50% inhibition of mitochondrial respiration at concentrations of 110 mu mol/liter or less. The mechanism of respiratory inhibition by the drugs was either a rotenone-, antimycin-, or oligomycin-like effect. One triazine derivative showed some specificity for inhibiting tumor cell respiration in comparison with normal cell respiration. Two naphthoquinone derivatives showed inhibition of respiration in in vivo treatments at chemotherapeutic doses. It was concluded that data on respiratory effects may assist in the interpretation of the results of in vivo and in vitro screening tests of the drugs, and that in some cases, as with the naphthoquinone derivatives, the effects on respiration could be related to the mechanism of action or the mechanism of toxicity of the drugs.

Animals↗
PubMedDate not supplied

Biological properties of a renotropic protein present in plasma of uninephrectomized rats.

The biological characteristics of a kidney growth factor (KGF) from uninephrectomized rat plasma have been studied. A crude preparation of this factor [Nephrol. Dial. Transplant. 4: 334-338, 1989] was further purified by hydrophobic interaction HPLC and gel filtration. KGF was found to be a heat- and trypsin-resistant protein. This factor stimulated dose-dependently DNA synthesis by the mouse kidney in vivo, and by either rat renal tubules or serum-deprived LLC-PK1 cells, in vitro. KGF also increased protein synthesis in these cells, in a dose-dependent manner. Moreover, KGF stimulated sodium uptake by these cells, associated with the maximal increase of protein synthesis. Our findings indicate that KGF is a potent renotropic protein which can play a key role in the renal compensatory growth after uninephrectomy.

Animals↗