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Biomedical subjects

A Alonso

Publications and source records attributed to A Alonso.

At least 361 records · Page 20Linked to original sources
PubMed1991

The F9-EC cell line as a model for the analysis of differentiation.

The teratocarcinoma stem cell line F9 has been widely used as a model for the analysis of molecular mechanisms associated with differentiation. This cell line has been considered to be nullipotent and able to differentiate into endodermal-like derivatives upon treatment with retinoic acid. Nevertheless, under definite culture conditions, F9 cells are able to differentiate into derivatives of all three germ layers. The F9 cells express characteristics of early mouse embryonal cells and possess all repression factors known to be present in cells of the early mouse embryogenesis. Induction of differentiation can be achieved not only by adding chemical agents to the culture medium but also by transfection of several oncogenic sequences. In somatic cell genetic experiments, immortalized, differentiated F9-like cells have been shown to express dominantly genes responsible for the appearance of the differentiated phenotype.

Animals↗
PubMed1991

Treatment for facial neuronitis: a new approach to Bell's palsy.

The presence of sensitive symptoms, symptoms of parasympathetic ganglion's affection, as well as signs of affection of other cranial nerves accompanying to Bell's palsy, led us to consider and treat this disorder as a symptom of motor lesion of a possible primary neuron inflammation. Although we have not found valid statistical correlations between the lesion and location patterns, we have found, however, that continues electromyographic studies, and the early treatment carried out, may be of great interest to avoid sequels. The treatment was focussed to eliminate both the possible cause and the inflammatory process, as to improve neuron regeneration. From 60 patients selected to enter this study, 91,66 percent recovered the motor function.

Adolescent↗
PubMed1991

Anemia of chronic renal failure: treatment with erythropoietin.

Twenty-three anemic children with end-stage renal failure (ESRD), aged 0.1-19.0 years (X +/- SD, 8.3 +/- 5.7 years), were treated with intravenous recombinant human erythropoietin (rHuEPO). Eleven were on conservative treatment and their estimated glomerular filtration rate (EGFR) was 11.8 +/- 3.8 ml/min/1.73 m2; 7 were on continuous ambulatory peritoneal dialysis (CAPD) and 5 on chronic hemodialysis. rHuEPO was given once a week in predialysis and CAPD children and thrice weekly in patients on hemodialysis. The initial dose of 50 U/kg/week was increased gradually up to a target hemoglobin of 10-12 g/dl. After 4.3 +/- 1.3 months of treatment, hemoglobin increased from 7.4 +/- 1.3 to 10.7 +/- 1.4 g/dl (p less than 0.001). An hemoglobin concentration of 11.4 +/- 0.9 g/dl was maintained with a rHuEPO dose of 289 +/- 86 U/kg/week. The response was similar in predialysis, CAPD, and hemodialysis children. No change in renal function was observed in predialysis children, EGFR being 11.8 +/- 3.8 and 10.8 +/- 1.7 ml/min/1.73 m2, before and after rHuEPO therapy. All children improved appetite, physical activity, and the sense of well-being. Four developed mild hypertension that was easily controlled with antihypertensive therapy. Heparin dose had to be increased during the hemodialysis sessions to avoid clotting of the filter. Serum calcium increased from 9.9 +/- 0.9 to 10.5 +/- 0.9 mg/dl (p less than 0.001). Serum aluminium levels also increased from 65 +/- 17 to 100 +/- 15 micrograms/l, p less than 0.01. A linear correlation (r = 0.58, p less than 0.01) between aluminium levels and rHuEPO dose was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia↗
PubMed1991

A clinical study of vestibular neuronitis.

By means of clinical and neurotological findings in 38 patients with vestibular Neuronitis, an analysis of the clinical-pathological manifestations, that may be included into this denomination, has been carried out. The probable etiology of this disease and the results of the tests performed have also been analyzed. In the light of these results the vestibular compensatory mechanisms, studied with later periodic tests, are discussed, and the conclusions on the prognosis and treatment of this entity derived.

Adolescent↗
PubMed1991

Ciprofloxacin in the treatment of gram-positive bacterial peritonitis in patients undergoing CAPD.

Fluoroquinolones may be a good alternative for the treatment of bacterial peritonitis in patients undergoing continuous ambulatory peritonitis dialysis (CAPD). To test their efficiency against Gram-positive bacteria, we treated with intraperitoneal (i.p.) ciprofloxac in 30 episodes of Gram-positive bacterial peritonitis without manifest tunnel infection of the peritoneal catheters. Treatment was sustained for 5 days, then orally for 10 further days. Clinical and bacteriological responses were satisfactory in 25 cases, but resolution of infection was slow in 5 cases of Staphylococcus aureus. The minimal inhibitory and bactericidal concentrations were 0.0625-0.50 and 0.125-1.0 micrograms/mL respectively, lower than the plasma and dialysate concentrations of the drug. Side effects were negligible. We conclude that ciprofloxacin provides a good therapeutic alternative to more widely used antibiotics for the empirical treatment of peritonitis in patients undergoing CAPD. However, combinations of antibiotics may be necessary, in Staphylococcus aureus peritonitis.

Administration, Oral↗
PubMed1990

Cholecystectomy and right colon cancer in Puerto Rico.

A case-control study was undertaken to evaluate the possible relationship between cholecystectomy and right colon cancer. Two hundred patients with adenocarcinoma of the cecum or ascending colon (diagnosed between 1984 and 1989) were compared with 200 matched neighborhood controls. Cholecystectomy history was obtained through interviews using structured questionnaires and subsequently validated from hospital records. A statistically significant association (odds ratio = 2.14) was found between right colon cancer and a history of prior cholecystectomy. The altered bile metabolism which occurs after removal of the gallbladder may have a carcinogenic effect on the right colon. Dietary habits of the colon cancer patients in our study were consistent with prior reports in the literature, showing that this group has a lower intake of vegetables and cereal fiber than the control population.

Aged↗
PubMed1990

Detergent solubilization of phospholipid vesicle. Effect of electric charge.

In order to explore the effect of electric charge on detergent solubilization of phospholipid bilayers, the interaction of nine electrically charged surfactants with neutral or electrically charged liposomes has been examined. The detergents belonged to the alkyl pyridinium, alkyl trimethylammonium or alkyl sulphate families. Large unilamellar liposomes formed by egg phosphatidylcholine plus or minus stearylamine or dicetyl phosphate were used. Solubilization was assessed as a decrease in light-scattering of the liposome suspensions. The results suggest that electrostatic forces do not play a significant role in the formation of mixed micelles and that hydrophobic interactions are by far the main forces involved in solubilization. In addition, from the study of thirty different liposome-surfactant systems, we have derived a series of empirical rules that may be useful in predicting the behaviour of untested surfactants: (i) the detergent concentration producing the onset of solubilization (Don) decreases as the alkyl chain length increases; the decrease follows a semi-logarithmic pattern in the case of alkyl pyridinium compounds; (ii) for surfactants with critical micellar concentrations (cmc) less than 6 x 10(-3) M, Don. is independent of the nature of the detergent and the bilayer composition; for detergents having cmc greater than 6 x 10(-3) M, Don. increases linearly with the cmc; and (iii) Don. varies linearly with the surfactant concentration that produces maximum solubilization.

Chemical Phenomena↗
PubMed1990

The lamellar to hexagonal phase transition in phosphatidylethanolamine liposomes: a fluorescence anisotropy study.

The steady-state anisotropy of trimethylammonium diphenylhexatriene fluorescence has been used to monitor the thermotropic lamellar to HII hexagonal phase transition in an unsaturated phosphatidylethanolamine. The transition is observed in lipid aggregates when they are heated above the transition temperature Th, as well as in diluted liposomes after aggregation above Th. Changes in fluorescence anisotropy are not observed with Ca(++)-induced fusion of phosphatidylserine vesicles, a process not involving hexagonal phase formation.

Diphenylhexatriene↗
PubMed1990

Haptoglobin subtyping by isoelectric focusing in miniaturized polyacrylamide gels rehydrated in presence of 2-mercaptoethanol.

A fast isoelectric focusing method for routine haptoglobin (Hp) subtyping is presented. This method is based on isoelectric focusing, under reducting conditions, of neuraminidase-treated plasma samples by using dry miniaturized (interelectrode distance: 55 mm) polyacrylamide gel, rehydrated in presence of 2-mercaptoethanol and a mixture of pharmalyte carrier ampholytes (pH 4-6.5 and pH 6-8) followed by immunoblotting. The presence of 2-mercaptoethanol in the gel prevented refolding of the Hp alpha and Hp beta chains during focusing, making it possible to obtain a sharp Hp band pattern with a clear separation of the different Hp alpha allelic products (1S, 1F, 2FS, 2SS and 2FF). A population study carried out with 250 unrelated individuals living in Central Spain is also presented.

Acrylic Resins↗
PubMed1990

Characterization of human catalase by isoelectric focusing in presence of urea.

Human catalase from erythrocytes and liver were analyzed by polyacrylamide gel isoelectric focusing in presence and absence of urea using two different pH gradients, namely pH 6-8 and pH 6.7-7.7. In presence of urea, human catalase focused in the pH range 6.75-7.0, slightly anodal to that of hemoglobin A. In narrow pH gradients, human erythrocyte catalase was microheterogeneous. Neuraminidase from different sources and peptide-N-glycosidase F were applied to investigate the presence of sialic acid and/or carbohydrate chains in human catalase. A shift in the focusing pattern of both erythrocyte and liver catalase towards the anode was observed after treatment with one of the commercially available neuroaminidase preparations. This unusual result could be related to a contaminating protease since no effect was observed when the catalases were treated in presence of a serine protease inhibitor. In contrast, bovine liver and Macaca erythrocyte catalase did not display any detectable change in their focusing patterns after treatment with any of the neuraminidase preparations.

Catalase↗
PubMed1990

Detection of genomic alterations in carcinogen-induced mouse liver tumors by DNA fingerprint analysis.

DNA fingerprint analysis was used to study structural abnormalities in the genome of mouse liver tumor cells. Liver tumors were induced in three strains of mice, namely C57BL/6J, C3H/He and B6C3F1, by a single injection of 20 micrograms/g body wt. diethylnitrosamine on day 15 after birth. DNA from liver tumors was digested with Hinfl restriction enzyme and hybridized on Southern blots with wild-type bacteriophage M13 DNA as probe. The resulting fingerprints of tumor DNA were compared with those of DNA from normal liver tissue. Genomic aberrations were detected in two out of 68 tumors analyzed, one stemming from a C57BL/6J and the other from a C3H/He mouse.

Animals↗
PubMed1990

Differentiation of EC cells in vitro by the fluorescent dye Hoechst 33342.

The fluorescent dye Hoechst 33342 is able to differentiate F9 EC cells at low concentrations. This differentiation is accompanied by synthesis of large amounts of laminin, production of a well-developed cytoskeleton, disappearance of the SSEA-1 antigen, and synthesis of large amounts of fibronectin, all characteristics of the primitive endoderm. The dye immediately blocks the cells at the S/G2 phase of the cell cycle and produces a complete arrest in proliferation. This effect is not specific for the nullipotent F9 cell line, as multipotent EC cell lines like PCC3, P19, and PCC4 can also be easily differentiated into the same pathway by treatment with the Hoechst dye. In contrast, the dye has no remarkable effects on terminal differentiated, immortalized cells like NIH 3T3 or the parietal endoderm-like cell PYS-2.

Animals↗
PubMed1990

Analysis of the expression of murine lambda genes transfected into immunocompetent cell lines.

Hybridoma cell lines were transfected with plasmids containing either a rearranged lambda 1 or a rearranged lambda 2 mouse gene. The levels of lambda-chains synthesized by these transfectants were very low or undetectable. Activation of the expression of the lambda 2 gene was achieved artificially by deleting a portion of the region upstream of the promoter. Analogous deletions in the fragment containing the lambda 1 gene did not result in gene activation suggesting that the upstream sequences of lambda 1 and lambda 2 genes have diverged enough to allow differential regulation of their expression. However, both genes were activated by insertion, at a position upstream of the promoter, of a fragment containing the K-chain gene enhancer. These results suggest that the complete set of sequence elements that mediate lambda gene activation during normal B-cell differentiation are not all contained in the fragments of genomic DNA cloned so far, and thus, at least some of them must be located at a considerable distance from the promoter.

Animals↗
PubMed1990

Postsynaptic Hebbian and non-Hebbian long-term potentiation of synaptic efficacy in the entorhinal cortex in slices and in the isolated adult guinea pig brain.

Long-term potentiation (LTP) was investigated in the mammalian entorhinal cortex by using two in vitro preparations, the isolated brain and the entorhinal cortex slice. Hebbian and non-Hebbian types of LTP appear to be present in layer II entorhinal cortex cells as demonstrated using two protocols: (i) tetanic stimulation of the piriform-entorhinal cortex afferent pathway to generate homosynaptic potentiation and (ii) postsynaptic subthreshold rhythmic membrane potential manipulation not paired to presynaptic activation, which gives rise to non-Hebbian LTP. The induction and the expression of both types of LTP were found to be dependent on activation of N-methyl-D-aspartate receptors as shown by their sensitivity to the receptor agonist D-2-amino-5-phosphonovalerate. This is in contrast to LTP in the hippocampus [Zalutsky, R. A. & Nicoll, R. A. (1990) Science 248, 1619-1624], where LTP is expressed by quisqualate receptors. Since, in the entorhinal cortex, LTP is linked to a selective increase of the N-methyl-D-aspartate-receptor-mediated synaptic responses, this enhancement is most likely due to postsynaptic factors.

2-Amino-5-phosphonovalerate↗
PubMed1990

GC subtyping and HIV infection in a Spanish population: no evidence of an association between GC subtypes and AIDS.

Group-specific component (GC) subtyping was performed by isoelectric focusing in 318 Spanish drug users at risk for infection or infected by HIV (85 HIV seronegatives, 111 HIV seropositives without symptoms, 89 seropositives with symptoms, 33 AIDS patients) and 187 healthy individuals. There was no significant association between GC subtypes and susceptibility to HIV infection and/or progression to AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Evaluation of key gluconeogenic enzymes in experimental biliary obstruction.

In order to evaluate the usefulness of key gluconeogenic enzymes, in relation to the markers commonly used (alkaline phosphatase and gamma-glutamyl transpeptidase) for the diagnose of cholestasis the serum activity of phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase and glucose-6-phosphatase has been measured in rats with bile-duct ligation. Among the gluconeogenic enzymes studied only phosphoenolpyruvate carboxykinase activity increased significantly in the first 48 hours after cholestasis, decreasing thereafter to normal values. Both alkaline phosphatase and gamma-glutamyl transpeptidase activities showed a very significant increase which persisted throughout the experiment. These results seem to indicate that in spite of the high organ specificity of these enzymes they do not appear to be useful for the diagnosis of cholestasis.

Alanine Transaminase↗