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Biomedical subjects

M C González

Publications and source records attributed to M C González.

At least 19 recordsLinked to original sources
PubMed1999

Fast separation of (poly)phenolic compounds from apples and pears by high-performance liquid chromatography with diode-array detection.

Polyphenolic compounds in apples and pears were analysed by HPLC on C18-modified silica. Gradient elution with phosphoric acid-methanol mixtures and phosphoric acid-acetonitrile mixtures gave complete separation of all polyphenolics of interest. The use of methanol as modifier was preferred because it provides a more rapid separation (20 min). Diode-array detection was used for the provisional identification of polyphenolic compounds not available as standards.

Acetonitriles↗
PubMed1998

High-performance liquid chromatography with diode-array detection for the determination of phenolic compounds in peel and pulp from different apple varieties.

Quantitative analysis of phenolic compounds from four apple varieties (Golden and Red Delicious, Granny Smith and Green Reineta) using high-performance liquid chromatography with diode-array detection was carried out. For each variety, both peel and pulp were analysed. The identification of phenolic compounds was made by comparing their retention times and UV spectra with those of standards. The results revealed differences between pulp and peel in all cases studied. The highest levels of phenolic compounds were found in the peel. High levels of catechins and flavonol glycosides, especially rutin, were found in apple peels. Chlorogenic acid was the major peak in the pulp for all apple varieties studied except for Granny Smith. Significant quantitative differences between the apple varieties were also found, the Golden Delicious variety showing the lowest content of phenolic compounds and Green Reineta variety the highest. The recovery of phenolic compounds from both peel and pulp was measured in all apple varieties. The values ranged between 95 and 105%, indicating close to quantitative recovery for the method used.

Caffeic Acids↗
PubMed1998

Sodium nitroprusside inhibits the tyrosine hydroxylase activity of the median eminence in the rat.

Nitric oxide (NO) has been involved in the modulation of various neuroendocrine responses. This work is a study of dose-response and time-course of the effect of intracerebroventricular (i.c.v.) administration of (NO) generator sodium nitroprusside (SNP), on tyrosine hydroxylase (TH) activity of the median eminence (ME) and serum prolactin levels, performed on conscious male rats. SNP (1, 5 and 10 microg) inhibited the TH activity of the ME, 15 min following injection in a dose-dependent way, although the effect was only significant with the highest dose, and also increased in a dose-dependent manner the serum prolactin levels. Both actions were transient but vanished at different times following injection of 10 microg of SNP. These results suggest that NO, released from SNP, inhibits the tuberoinfundibular dopaminergic neurons of the basal hypothalamus to stimulate prolactin secretion.

Animals↗
PubMed1998

Methylene blue inhibits stimulatory effect of sodium nitroprusside but not of 3-morpholino sydnonimine on prolactin secretion in freely moving male rats.

Previously we reported that intracerebroventricular (i.c.v.) administration of nitric oxide (NO) donors, sodium nitroprusside (SNP) (1-10 microg), and 3-morpholino-sydnonimine (SIN-1) (10-100 microg), induced dose-dependent increases in plasma prolactin levels of freely moving male rats, suggesting a role of NO in the control of prolactin secretion. The present results show that i.c.v. pretreatment with methylene blue (MB) (30 microg), a guanylyl cyclase inhibitor, significantly reduced the effects of microinjections of SNP (3 and 5 microg), however, this did not modify the stimulatory action of SIN-1 (30 microg) on plasma prolactin levels of conscious male rats. Alone, MB did not modify basal prolactin levels. These results suggest different mechanisms of action of SNP and SIN-1 to stimulate prolactin secretion in vivo. Activation of soluble guanylyl cyclase seems to mediate the neuroendocrine action of NO released from SNP but not of SIN-1. Different cellular distribution of NO generating activity from these donors as well as the possible generation of other radicals simultaneously with NO from SIN-1 could explain these differences.

Animals↗
PubMed1998

Expression and localization of phosphoenolpyruvate carboxylase in developing and germinating wheat grains.

Phosphoenolpyruvate carboxylase (PEPC) activity and corresponding mRNA levels were investigated in developing and germinating wheat (Triticum aestivum) grains. During grain development PEPC activity increased to reach a maximum 15 d postanthesis. Western-blot experiments detected two main PEPC polypeptides with apparent molecular masses of 108 and 103 kD. The most abundant 103-kD PEPC subunit remained almost constant throughout the process of grain development and in the scutellum and aleurone layer of germinating grains. The less-abundant 108-kD polypeptide progressively disappeared during the second half of grain development and was newly synthesized in the scutellum and aleurone layer of germinating grains. PEPC mRNA was detected throughout the process of grain development; however, in germinating grains PEPC mRNA accumulated transiently in the scutellum and aleurone layer, showing a sharp maximum 24 h after imbibition. Immunolocalization studies revealed the presence of the enzyme in tissues with a high metabolic activity, as well as in the vascular tissue of the crease area of developing grains. A clear increase in PEPC was observed in the scutellar epithelium of grains 24 h after imbibition. The data suggest that the transiently formed PEPC mRNA in the scutellar epithelium encodes the 108-kD PEPC subunit.

Gene Expression Regulation, Developmental↗
PubMed1998

[Transthoracic needle aspiration biopsy. The diagnostic accuracy of pulmonary lesions].

We performed 91 transthoracic functions, under fluoroscopy, sonographically or by computed tomography control, at Clinic Hospital in Valencia. The procedures was performed with Chiba needle 22 gauges while the cytopathologist was present. Maximum number of needle passes was four. Malignant diagnosis has been obtained in 64.8% of cases, in 12 patients a benign diagnosis was obtained and confirmed, 13 cases were false negative and the specimen was insufficient for diagnosis in 7 (5 of them lesions had a diameter less than 2 cm). The study showed 82% for sensitivity, 100% for specificity and 85% for accuracy. The punction was guided by fluoroscopy in 49 patients, by sonography in 6 and by computed tomography control in 36. The accuracy diagnosis for fluoroscopy guidance was 96%. The complications were 9 (9.9%): Two patients presented minor hemoptysis resolved spontaneously, 6 patients showed minor pneumothorax and one patient was treated a cause of a large pneumothorax. We concluded that transthoracic biopsy is a simple and save technique that can provide a high diagnosis accuracy in patients with pulmonary pathology.

Biopsy, Needle↗
PubMed1996

Acetogenins from Annonaceae, inhibitors of mitochondrial complex I.

One-hundred and twenty-eight different linear, epoxy, mono-tetrahydrofuran, bis-tetrahydrofuran or tri-tetrahydrofuran acetogenins have been isolated from the Annonaceae. These new secondary metabolites are potent cytotoxic inhibitors of the mitochondrial NADH:ubiquinone oxidoreductase (complex I of the respiratory chain).

Enzyme Inhibitors↗
PubMed1996

Annosenegalin and annogalene: two cytotoxic mono-tetrahydrofuran acetogenins from Annona senegalensis and Annona cherimolia.

Two new cytotoxic mono-tetrahydrofuran acetongenins, annosenegalin and annogalene, have been isolated from the cytotoxic methanolic extract of Annona senegalensis and A. cherimolia seeds. Their structures were established on the basis of 1D and 2D NMR spectroscopic techniques. Annosenegalin belongs to the rare type of C37 mono-tetrahydrofuran acetogenins, and annogalene is an olefinic acetogenin.

Animals↗
PubMed1996

[Measurement of total serum IgE by enzyme immunoassay with three commercial reagents].

We measured total serum IgE in 14 patients with allergic diseases and 16 healthy subjects, using three commercial ELISA kits. The correlation of results among the three kits was analyzed using Passing and Bablock regression parameters. Results show that measurements of the different kits do not coincide. One kit shows differences using sera from normal subjects. There is no correlation among kits when using sera from allergic patients. It is concluded that it is not possible to determine exactly the amount of IgE using these kits, specially in subjects with elevated levels.

Adolescent↗
PubMed1994

Interleukin-1 beta stimulates tyrosine hydroxylase activity in the median eminence.

The effects of intracerebroventricularly (i.c.v.) injected interleukin-1 beta (IL-1 beta) on tyrosine hydroxylase (TH) activity in the median eminence and on serum adrenocorticotropin hormone (ACTH) and prolactin (PRL) levels were studied in freely moving male rats chronically implanted with i.c.v. cannulas. IL-1 beta stimulated TH activity of the median eminence in a dose-dependent manner. Intracerebroventricular injections of 100 ng and 200 ng IL-1 beta significantly increased TH activity in the median eminence by 40.6% and 74.7% respectively over the saline-injected control group. The stimulation of ACTH secretion was statistically significant for all doses used, however i.c.v. injections of IL-1 beta failed to elicit significant changes in the serum PRL concentrations. These results suggest that IL-1 beta increases dopaminergic activity of the medial basal hypothalamus to produce its neuroendocrine effects.

Adrenocorticotropic Hormone↗
PubMed1990

Role of monokines in control of anterior pituitary hormone release.

It has long been known that endogenous pyrogen, released as a result of injection of typhoid vaccine or in response to infection, produces fever and increases ACTH secretion. Recent studies have indicated that endogenous pyrogen is, at least in part, IL-1. This monokine has now been shown to activate the release of ACTH by a hypothalamic mechanism with release of CRF and possibly vasopressin, which stimulates the corticotrophs. There may also be a pituitary action to stimulate the release of ACTH directly. In our experiments we showed that IL-1 at low but not higher doses appears to act intrahypothalamically to stimulate GH and PRL release and to inhibit TSH release. In the meantime, another monokine, cachectin, was isolated and its structure determined. We have found that this monokine can act following its third ventricular injection to stimulate ACTH, PRL, and GH release and to inhibit TSH release, at least in part, by release of prostaglandins since indomethacin, an inhibitor of prostaglandin synthesis, produced a blockade of the responses except for those of ACTH. This peptide also has highly potent effects to alter pituitary hormone release by direct action on the pituitary to stimulate ACTH, GH, and TSH and to a slight extent PRL release. These actions appear to involve prostaglandins since indomethacin blocks all of the effects except for the effect on ACTH secretion. This monokine also produces a dose-related lowering of anterior pituitary cyclic AMP levels. When the monokine was incubated along with somatostatin, the lowering of cyclic AMP was reversed, and a potent PRL-releasing effect of the monokine was visible. We have begun studies with a third monokine, gamma interferon, which indicate that it stimulates ACTH release but suppresses plasma GH and TSH levels by a hypothalamic action. It is apparent that these various monokines have powerful effects to alter hypothalamic-pituitary function and that they probably mediate most of the effects of infections on the release of anterior pituitary hormones.

Animals↗
PubMed1988

Different distribution of ELI-perikarya in rat mesencephalon using various injection sites for colchicine.

In the present work, using the indirect peroxidase-labelled antibody technique, we made a comparative study about the distribution of Met-enkephalin-like-immunoreactive (ELI)-cell bodies in rat mesencephalon; comparing animals that received colchicine into the lateral ventricle and animals that got the colchicine injected into different cerebral nuclei. We discuss the possibility that the local intracerebral injections are more effective than the intraventricular ones and we show that the results depend on the injection place. So, we think that there are possible met-enkephalinergic connections between the injected region and their corresponding immunoreactive mesencephalic nuclei.

Animals↗
PubMed1988

[C-reactive protein, lactate and LDH isoenzymes in the cerebrospinal fluid in the diagnosis in childhood meningitis].

C reactive protein lactate and LDH isoenzymes were quantified in CSF of 32 children with meningitis (27 bacterial and 5 viral). Results in cases with bacterial meningitis were as follows. C reactive protein sensitivity was 11.1% and specificity was 100%. Lactate sensitivity was 33.3% and its specificity was 80%. LDH1 and LDH5 had a sensitivity of 44.4%, and specificities of 100 and 60% respectively. Considering these results an has believe that none of these tests is definitive in diagnosis of bacterial meningitis in children.

C-Reactive Protein↗
PubMed1988

Platelet antiaggregatory effect of triflusal in human whole blood.

An in vitro and ex vivo study has been made to determine the inhibition of platelet aggregation in human whole blood (WB) and platelet rich plasma by triflusal and its main metabolite HTB (2-hydroxy-4-trifluoromethylbenzoic acid). Triflusal was administered orally at 300 mg x 2/day, for 15 days, to 13 healthy volunteers (ex vivo tests). Triflusal and HTB, at concentrations lower than 1 mM, produced a significant inhibition of platelet aggregation induced by ADP (2.5 microM, final) and collagen (1 microgram/ml, final) in PRP, while about 50% inhibition was induced in WB samples at 0.12 mM. Ex vivo studies also revealed a stronger inhibitory effect of triflusal in WB samples against several inducers; differences were particularly pronounced against ADP (10.6 times more potent in WB). These results suggest an important role of red blood cells and/or leukocytes in the mechanism of action of triflusal. The antiplatelet effect of triflusal in WB was modified when incubated with HTB at therapeutic concentrations. The IC50 value against collagen increased from 82 to 140 microM with 37.5 microM HTB, but decreased in a dose-dependent manner when incubated with higher concentrations of HTB, suggesting that inhibition of platelet cyclooxygenase by HTB masks its negative interaction with triflusal.

Adenosine Diphosphate↗
PubMed1986

Characterization of a dopaminergic receptor that modulates adrenomedullary catecholamine release.

Nicotine evokes the release of catecholamines from bovine adrenal glands perfused with oxygenated Krebs-bicarbonate solution. Two 2-min pulses of 5 microM nicotine, at 40-min intervals (S1 and S2), gave net catecholamine outputs of 45.2 +/- 3.6 and 29.1 +/- 3.5 micrograms/8 min, respectively. Apomorphine (1 or 10 microM) markedly inhibited catecholamine release during S2 to 9.1 +/- 2.2 and 0.5 micrograms/8 min, respectively. Haloperidol (0.5 microM) reversed the inhibitory effects of apomorphine. Haloperidol alone enhanced catecholamine release induced by nicotine to 67.9 +/- 7.9 micrograms/8 min. [3H]Spiperone binds to adrenomedullary membranes with a KD of 0.24 nM and a Bmax of 117 fmol/mg of protein. Whereas spiperone and haloperidol potently displaced such binding, 3,4-dihydroxyphenylethylamine (dopamine) and sulpiride were poorer displacers, and SCH23390, prazosin, phenoxybenzamine, propranolol, BAY-K-8644, and nitrendipine did not displace [3H]spiperone bound. These data strongly suggest that, as in the cat, the bovine adrenal medulla chromaffin cell contains a dopaminergic receptor that modulates the catecholamine secretory process triggered by stimulation of the nicotinic cholinoceptor. Such a receptor seems to be of the D2 type and might be involved in a sympatho-adrenal cooperative mechanism contributing to the maintenance of cardiovascular homeostasis during stressful situations as well as to the pathogenesis of hypertension. If so, selective dopaminergic agonists might prove clinically useful in the treatment of hypertension.

Adrenal Medulla↗
PubMed1985

[Fetal rhabdomyomatous nephroblastoma: study of 2 cases and review of the literature].

Report of two cases of Fetal Rhabdomyomatous Nephroblastoma, a cytodifferentiated variant of Wilms' tumor. The incidence of this rare variant is of 2.10% in our material (88 nephroblastomas in a sixteen years period). The patients were ten months and two years old. Bilateral tumors were discovered in both patients. Preoperative radiotherapy was given but no reduction of the tumors size was obtained. Microscopically, benign looking striated muscle is the predominant component of the tumors, with scare foci of epithelial elements. The low age of presentation, high incidence of bilaterality and the peculiar intrapelvic renal growth are three relevant characteristics in the 35 cases previously reported as well as in these two new cases, that distinguish Fetal Rhabdomyomatous Nephroblastoma from conventional Wilms' tumor.

Female↗