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Biomedical subjects

F Zamora

Publications and source records attributed to F Zamora.

16 recordsLinked to original sources
PubMed2006

Adsorption of p-nitrophenol on activated carbon fixed-bed.

Carbon fixed-beds are usually used to remove organic contaminants. Adsorption in a carbon filter is a dynamic, non-steady process which is not yet completely understood. The objective of this paper is to establish a methodology to simplify the study of this process based on the wave theory, rapid small-scale column test and experimental design/surface response analysis. The constant pattern wave hypothesis was confirmed by the experimental data. The influence of the inlet concentration of p-nitrophenol and the flow rate on dynamic adsorption was studied at 20 degrees C following a central composite design using a second-order model. Both parameters have an important influence on the response variables studied. The methodology used is a useful tool for studying the dynamic process and shows interactions that are difficult to verify by the classical step-by-step method.

Adsorption↗
PubMed2005

Influence of ethanol concentration on the extraction of color and phenolic compounds from the skin and seeds of Tempranillo grapes at different stages of ripening.

The aim of this paper is to study how grape ripeness and ethanol concentration affect the extraction of color and phenolic compounds from skins and seeds during the maceration/fermentation process. Simulated maceration assays were carried out with the grapes at three stages of berry development (vitis vinifera cv. Tempranillo) and different percentages of ethanol in the maceration media. Both ripeness and ethanol content have a considerable effect on the extraction of color and phenolic compounds. Of these two factors, ripeness increases the extractability most. The presence of ethanol in the medium facilitates anthocyanin and especially proanthocyanidin extraction, but it also decreases copigmentation phenomena, which can decrease the color intensity. The higher the ethanol concentration is in the maceration media, the higher the astringency of proanthocyanidins.

Color↗
PubMed1999

5,5'-Diuracilyl Species from Uracil and

Not only UV radiation can bring about the dimerization of the pyrimidine nucleobase uracil, a metal ion can as well! The reaction proceeds by a reductive elimination process of two cis-oriented uracil entities, each bonded to Au(III) through C5 [Eq. (a)]. R/R'=H/CH(3), CH(3)/CH(3), H,C(5)H(9)O(4)

Journal Article↗
PubMed1998

Molecular analysis of yeast population dynamics: effect of sulphur dioxide and inoculum on must fermentation.

The effects of sulphur dioxide and a commercial starter inoculum on yeast population dynamics have been analysed by a molecular approach. Yeast identification from fermenting Carinyena grape musts was performed by RFLP's of mtDNA and rRNA-coding DNA. As expected, the use of a commercial inoculum speeded up the start of fermentation, while SO2 addition limited the development of non-Saccharomyces species. However, this effect was also observed with yeast inoculation. Further analysis of population dynamics could lead to a recommendation for the reduction of the dosage of SO2 by the addition of appropriate inoculum of yeasts in the must. Furthermore, the timing of inoculum addition could be modified to allow a proper contribution of non-Saccharomyces species. Molecular biology analysis of population dynamics could provide a tool to efficiently reduce the dosage of SO2 and adjust the timing of inoculum addition.

DNA, Mitochondrial↗
PubMed1993

Palladium (II) compounds of putrescine and spermine. Synthesis, characterization, and DNA-binding and antitumor properties.

The reaction of putrescine (Put) with K2PdCl4 and PdCl2 resulted in the synthesis of compounds of formula [PutH2][PdCl4] and [Pd2Cl4(Put)2]. Compounds of formula [PdCl2(SpermH2)][PdCl4] and [Pd2Cl4(Sperm)] have been also synthesized by reaction of spermine (Sperm) with K2PdCl4. The structure of all these compounds has been analyzed by IR and 1H NMR. UV and CD spectroscopic data have shown that all the Pd(II)-polyamine compounds synthesized induce conformational changes in the circular forms of plasmid DNA. Determinations by electrophoresis in agarose gels of the mobility of the DNA in drug:DNA complexes indicated that only the Pd(II)-putrescine compounds have the ability to induce significant conformational changes in the covalently closed circular (ccc) form of the pUC8 plasmid DNA. The Pd(II)-putrescine and Pd(II)-spermine compounds were also assayed for in vitro antiproliferative activity against MDA-MB 468 and HL-60 human cancer cells. The results suggest that the putrescine complexes may be regarded as potential antitumor agents because the ID50 value of all of the Pd(II)-putrescine complexes is twofold lower than the ID50 of cis-DDP. Our data also show that, on the other hand, the Pd(II)-spermine compounds have low antiproliferative activity.

Antineoplastic Agents↗
PubMed1993

Purification and characterisation of a polymorphic low M(r) bovine muscle cysteine proteinase inhibitor: structural identity with fatty-acid-binding proteins.

Three low molecular mass cysteine proteinase inhibitors were purified from a bovine skeletal muscle crude extract using a three-step procedure. The crude extract was first subjected to gel filtration on a Sephadex G100 column which separated five active fractions (F-I to F-V). Three papain inhibitors, P1, P2 and P3, were fractionated from the F-V fraction by chromatofocalisation on a poly buffer exchanger column. Purification was completed by chromatography on a Mono Q column. After SDS-PAGE, the three inhibitors showed only one band with an M(r) of 14,300. P1, P2 and P3 appeared to be highly resistant to temperature (40-90 degrees C), pH (3-10), reducing agents (5-50 mM) and to be specific for cysteine proteinases since no activity was detected against either serine or aspartyl proteinases. Although to a varying extent, P1, P2 and P3 inhibited papain, cathepsin B and cathepsin L. Analysis of the peptide mixtures of these inhibitors by RP-HPLC after hydrolysis with CNBr or aspartly endoproteinase N together with their amino acid composition revealed that P1, P2 and P3 cysteine proteinase inhibitors are isoforms of the same protein. As their N-terminal ends were blocked, partial sequence of some of these peptides was determined. Computer search in protein identification resources did not reveal any homology of these sequences with proteinase inhibitors of known primary structure. In contrast, they matched well with different parts of the total sequence of a fatty acid binding protein isolated from bovine heart. This homology was supported by the ability of these inhibitors to bind long chain fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkylation↗
PubMed1992

Palladium(II) salt and complexes of spermidine with a six-member chelate ring. Synthesis, characterization, and initial DNA-binding and antitumor studies.

By reaction of spermidine trihydrochloride with K2PdCl4 and PdCl2 at different pH's, we have synthesized the [sperH3]2[PdCl4]3 (I), [PdCl2(sperH)]2[PdCl4] (II), and [(PdCl2)3(sper)2] (III) compounds. The structure of these compounds was studied by IR and 1H NMR; complex II was analyzed by x-ray diffraction. In this complex the spermidine is attached to the PdCl2 group forming a six-member chelate ring with a protonated terminal amine group. The crystal of [PdCl2(sperH)]2[PdCl4] x 2H2O (II) is monoclinic, P2(1)/n, with a = 7.023(1) A, b = 12.662(1) A, c = 18.435(3) A, and beta = 99.95(1) degrees, Z = 4, R = 0.051, and Rw = 0.058 on the basis of 2690 independent reflections. We have compared the antitumor activity in vitro against the isolated human breast carcinoma MDA-MB 468 cell line of compounds I, II, and III with that of cis-diamminedichloroplatinum(II), cis-DDP. The results show that compounds III and III have values of ID50 similar (0.74 microgram/ml) or even lower (0.56 microgram/ml) than cis-DDP (0.80 microgram/ml). We also observed that compounds I, II, and III have the ability to induce conformational changes in covalently closed circular (ccc) form of the pUC8 plasmid DNA. Compounds II and III also induce conformational changes in the open circular (oc) form of this plasmid.

Antineoplastic Agents↗
PubMed1991

Parallel modulation of brown adipose tissue GDP-binding, substrate uptake and (Na(+)-K+)-ATPase activity in the rat.

Brown adipose tissue (Na(+)-K+)-ATPase activity, in vitro glucose uptake and 2-aminoisobutyric acid uptake, as well as mitochondrial GDP-binding and succinate dehydrogenase activity were determined in order to study the relationship between these parameters in control, cold acclimated and cafeteria-fed rats. GDP-binding, (Na(+)-K+)-ATPase and glucose uptake were increased in interscapular brown adipose tissue from cold-acclimated and cafeteria-fed rats, whereas 2-aminoisobutyric acid uptake was only increased in cafeteria-fed rats. GDP-binding and (Na(+)-K+)-ATPase activity showed a high correlation coefficient suggesting a parallel modulation of both systems, which would probably share a common regulation mechanism.

Adipose Tissue, Brown↗
PubMed1989

Brown adipose tissue (Na+-K+)-ATPase activity and substrate uptake during the breeding cycle of rats.

Brown adipose tissue (Na+-K+)-ATPase activity, in vitro glucose and 2-aminoisobutyric acid uptake, as well as mitochondrial GDP-binding and succinate dehydrogenase activity were determined in order to study the relationship between these parameters and the thermogenic status. Analysis were carried out on control animal, pregnant rats, dams and pups during lactation, GDP-binding, (Na+-K+)-ATPase and glucose uptake were found to be decreased in brown adipose tissue from pregnant rats and dams, and increased in pups, 2-aminoisobutyric acid uptake was only increased in pups, but no changes were observed in the other experimental groups tested. GDP-binding and (Na+-K+)-ATPase activity showed a parallelism which suggests that the enzyme is a good index of thermogenic status of the animal.

Adipose Tissue, Brown↗
PubMed1988

In vitro glucose and 2-aminoisobutyric acid uptake by rat interscapular brown adipose tissue.

The dependence upon substrate and insulin concentrations, as well as on sodium and potassium concentrations in the medium of the uptake of glucose and 2-aminoisobutyric acid, was determined for fragments of brown and white adipose tissues incubated in vitro. Brown adipose tissue showed a high capacity for glucose uptake at high glucose concentrations, this uptake being dependent on both glucose and insulin concentration. White adipose tissue showed much more limited uptake capabilities. The presence of Na+ and K+ had little effect on the uptake. The uptake of 2-aminoisobutyric acid was similar in both adipose tissues, being enhanced by physiological levels of insulin and depressed by ouabain. This amino acid transport was dependent on Na+ and K+ concentrations, and the overall transporting capability was two to three orders of magnitude lower than that for glucose. It was concluded that amino acids could not play a significant role as bulk thermogenic substrates for brown adipose tissue, as their transporters lack the plasticity of response to high substrate and insulin concentrations which characterize brown adipose tissue uptake of glucose.

Adenosine Diphosphate↗
PubMed1988

Some pitfalls and considerations of plasma ammonia estimation.

Several approaches to the estimation of plasma ammonia have been tested and compared: indophenol, Nessler, iodometric techniques were studied as well as enzymatic spectrophotometric and radiometric methods. Their lower safe limits of estimation were determined and it was found that most of them were not viable for plasma estimations because of its very low ammonia levels. The need for a concentration/purification step and the lack of repetability in this phase at very low concentrations, made very unreliable the utilization of all methods studied except for the enzymatic radiometric method tested that was barely usable for plasma ammonia estimations.

Ammonia↗
PubMed1987

(Na+-K+)-ATPase activities in rat tissues during pregnancy.

(Na+-K+)-ATPase activities of liver, hind leg skeletal muscle, brain, perirenal white adipose tissue, interscapular brown adipose tissue and blood as well as placenta, fetal liver and fetal blood were determined in virgin rats and pregnant rats on days 12, 19 and 21 of gestation in order to evaluate its relative contribution either to metabolite transport processes or/and to thermogenesis during pregnancy. No changes were found in (Na+-K+)-ATPase activity in liver, blood and white adipose tissue in pregnant rats versus controls. (Na+-K+)-ATPase activity from muscle, brain and interscapular brown adipose tissue decreased during pregnancy and placenta showed an increase of (Na+-K+)-ATPase on day 21 of gestation in respect to day 12. No significant changes were observed either in fetal liver or fetal blood.

Adipose Tissue↗
PubMedDate not supplied

[Clinical features of cerebral toxoplasmosis in Cuban patients with AIDS].

INTRODUCTION: Neurotoxoplasmosis (NTX) is one of the commonest opportunist infections in patients infected by the human immunodeficiency virus. It presents with a variety of clinical features in the immunocompromised patient. PATIENTS AND METHODS: We made a horizontal retrospective descriptive study of 88 patients with a diagnosis of NTX treated in the Pedro Kour Institute during a three years period. Our aim was to find which were the most common forms of clinical presentation in our setting and to evaluate the use of paraclinical examinations in reaching the presumptive diagnosis. The patients had clinical examinations, CSF studies, detection of indirect immunofluorescence titres (IFI) for Toxoplasma, imaging studies (CAT) and lymphocyte counts. RESULTS: The commonest symptoms were: headache in 79%, fever in 55.68%, motor defect in 44.31% and disorders of consciousness in 29.54% of the patients. The IFI titres were negative in 31.54% of the patients, between 1/16 and 1/32 in 38.34% and between 1/64 and 1/1,024 in only 30.07% of cases. The T CD4+ lymphocyte count was less than 200 cells in 66.7% of the patients; 72% of imaging studies showed typical lesions, in association with other disorders in 38% of the cases (lymphomas, cryptococcosis, tuberculous meningoencephalitis and cytomegalovirus encephalitis). CONCLUSIONS: NTX in a patient with AIDS often presents in our setting with headache and fever, motor deficit and alterations of consciousness. The diagnosis should be confirmed by immunological or imaging studies since in this disease serology and CSF studies are less specific.

Acquired Immunodeficiency Syndrome↗