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Biomedical subjects

C Díaz

Publications and source records attributed to C Díaz.

At least 109 records · Page 6Linked to original sources
PubMed1996

[Effect of energy density and fat level of milk formulas on subsequent food and energy intake in preschool children].

The aim of this study was to examine the effects of two levels of energy intakes and two levels of fat at breakfast, on the food and energy intakes in subsequent meal (lunch). The study was performed in 51 children both genders, with ages ranging from 24 to 48 months, attending a day care center. The children selected had normal nutritional status (weight/height index) according to the NCHS standards. The food intake was determined by differential weighing and energy intake was calculated from proximal analysis. The energy densities of the cow's milk formula used were 0.8 and 1.2 kcal/g, resulting in a total energy offer (breakfast) of 267.5 and 367.5 kcal respectively, the fat levels were 6.3 and 0.9 g/250 g of formula, using the design 2 x 2 factorial. In the study, 720 observations of food intake were conducted in those children consuming higher than 75% of the total food offered at breakfast. In the lunch-time were offered in alternated form two preparations with an 0.97 kcal/g of energy density. The results demonstrated that the children consumed significantly higher energy amounts in the subsequent meal, after being fed the high fat and lower energy-content breakfast. When the total energy intake (breakfast + lunch) was compared these results show that the caloric difference of breakfast was reduced and the degree of reduction was influenced by the fat level. These results show evidence for partial caloric compensation of 67% in the higher-fat level, and only 34% for the children with the lower of fat-level. It is conclude that the energy intake and fat intake at breakfast influences the energy intake at the subsequent meal. These findings are important to the preschool children's feeding with risk of malnutrition.

Animals↗
PubMed1996

[3 combinations of esterases and their relation with the resistance to organophosphate, carbamate, and pyrethroid insecticides in Culex quinquefasciatus Say, 1823 (Diptera: Culicidae) in Cuba].

The possible relationship between different patterns of esterases and the resistance to various types of insecticides was analyzed by bioassays, biochemical tests, and electrophoresis carried out in a population of Culex quinquefasciatus from Camagüey and in three colonies obtained from it by family selection. The original population was heterogeneous and presented 8 combinations of esterases in polyacrylamide gel. A3A6B6, B1B6 and B1A6B6 were the most frequent of them and characterized each selected colony. Every studied colony, including the parental one, showed different levels of resistance to diverse insecticides. Only the resistance to propoxur showed less variation. In every colony it seems to exist a combination of resistance mechanisms; however, the differences found in tests with DEF synergized insecticides show that the different bands of zymograms may represent esterases contributing in a different way to resistance.

Animals↗
PubMed1996

[The evolution of resistance in a Culex quinquefasciatus strain starting from selection with the pyrethroid insecticide lambdacyhalothrin].

The resistance change to different insecticides in Culex quinquesfasciatus strain select at the laboratory with doses of pyrethroid lambdacyhalothrin that would cause a larva mortality of 90% were studied. It was attained an increase of the resistance to this insecticide of 144.5 times compared with the original level, and it was obtained a resistant strain (287x). There was an increase of the levels of resistance to methyl-pyrimifos (2.4 times), propoxur (6 times), DDT (5.2 times), clorpirifos (22 time), cypermethrin (67.5 times), and deltamethrin (20.2 times). The frequencies of the genes that codify for the elevated esterases enzymes and for the modified acetylcholinesterase reached their maximum value. Significant changes were observed in the phenotypes for esterases in the electrophoresis in polyacrylamide gels. It was detected synergism of DEF and PB with lambdacyhalothrin. Therefore, the elevated esterases and the esterases of multiple function may contribute to resistance.

Acetylcholinesterase↗
PubMed1995

Delta-endotoxins induce cation channels in Spodoptera frugiperda brush border membranes in suspension and in planar lipid bilayers.

Membrane potential measurements using a fluorescent dye indicated that two specific toxins active against Spodoptera frugiperda larvae (CryIC and CryID) cause immediate permeability changes in midgut epithelial brush border membrane vesicles (BBMV). The initial response and the sustained permeability change are cationic, not very K+ selective, and occur at in vivo lethal doses (nM). The toxin response has a different ion selectivity and is more sensitive to Ba2+ than the intrinsic cation permeability of BBMV. Experiments incorporating BBMV into planar lipid bilayers (PLB) demonstrated that these vesicles contain cation channels (31, 47 and 76 pS). A 2-40 fold conductance increase was induced by nM concentrations of toxin in PLB containing BBMV. Cationic single channel transitions of 50, 106, 360 and 752 pS were resolved. Thus, Bacillus thuringiensis delta-endotoxins induce an increase in cation membrane permeability involving ion channels in BBMV-containing functional receptors.

Animals↗
PubMed1995

Purification and characterization of myotoxin IV, a phospholipase A2 variant, from Bothrops asper snake venom.

A basic myotoxic protein was purified from Bothrops asper venom. Like other basic Bothrops myotoxins, myotoxin IV induces acute muscle damage after intramuscular injection in mice and disrupts negatively charged liposomes but not positively charged ones. Furthermore, this protein exerts a weak anticoagulant effect only at concentrations of 40 micrograms/ml or higher, and is devoid of phospholipase A2 activity. Rabbit polyclonal antibodies to B. asper myotoxin II, a related lysine-49 isoform, cross-react strongly with myotoxin IV by enzyme immunoassay, indicating a high degree of antigenic similarity between these two proteins. The fact that both toxins have similar amino acid compositions and amino-terminal sequences, including leucine-5 and glutamine-11, 2 amino acid residues conserved in all lysine-49 phospholipase A2 variants purified, strongly suggests that B. asper myotoxin IV is a lysine-49 phospholipase A2.

Amino Acid Sequence↗
PubMed1995

Isolation and characterization of a metalloproteinase with weak hemorrhagic activity from the venom of the snake Bothrops asper (terciopelo).

A metalloproteinase, named BaP1, was purified to homogeneity from the venom of Bothrops asper (Pacific region) of Costa Rica by ion-exchange chromatography on CM-Sephadex and gel filtration on Sephacryl S-200. The enzyme has a mol. wt of 24,000 and contains few Cys and high numbers of Asp, Leu, Ser and Glu. BaP1 hydrolyzes casein, hide powder azure and fibrinogen, having an optimal pH of 8.0. It rapidly digests the A alpha-chain of fibrinogen and, later on, the B beta-chain, leaving the gamma-chain unaffected. Chelating agents (EDTA and 1,10-phenanthroline) inhibited proteolytic activity, whereas 2-mercaptoethanol and soybean trypsin inhibitor did not affect this activity. BaP1 has a weak hemorrhagic activity, with a minimum hemorrhagic dose of 20 micrograms; this activity was inhibited by EDTA and was abolished after incubation at 60 degrees C. In addition, BaP1 induces edema and a mild myotoxic effect, lacking coagulant, defibrinating and lethal effects.

Amino Acids↗
PubMed1995

Iron, copper and zinc levels in urine: relationship to various individual factors.

Urinary Fe, Cu and Zn levels were determined in healthy people from S/C de Tenerife. Males showed higher (p < 0.01) urinary levels (micrograms/L and microgram per day) of Zn than females. However, females had higher daily urinary Fe and Cu excretions per kg of body weight (p < 0.05) than males. Urinary metal concentration, expressed as mg metal per g CT, better reflects daily excretion. Urinary levels of Zn and Cu were within the reference values, but the urinary levels of Fe were lower than that in most of the published data. An increase in daily Fe, Cu and Zn excretion (micrograms per day) with age up to 30 years was observed. An increase with weight and height was also observed. Concentrations and excretions of Zn were significantly (p < 0.015) lower when the urinary pH was above 7. With respect to the frequency of consumption of rich protein food, rich fiber food, coffee, tobacco, or alcohol, only significantly (p = 0.015) higher Zn concentrations and higher (p = 0.091) excretions were found in people that consume alcohol more than 3 times a week. A significant depletion of urinary Zn and Cu concentration and Fe excretion was found in the subjects who usually did physical exercise. Positive intermetallic correlations among the concentrations and excretions of the metals investigated were observed.

Adolescent↗
PubMed1995

[The association of resistance to organophosphate, carbamate and pyrethroid insecticides with the mechanisms of resistance observed in Culex quinquefasciatus strains from Ciudad de La Habana province].

The mechanisms of resistance in Culex quinquefasciatus from 6 municipalities of Havana City were studied in order to determine their genetic frequency. Increased esterases and altered acetylcholinesterase are still being the major resistance mechanisms in Havana City. The mechanisms of esterases is of high frequency, followed by altered acetylcholinestenase. Resistance to cholorpirifos was found for the first time in Culex quinquefasciatus, while resistance of malathion and carbamate propoxur is maintained, and deterioration to pyrethroid susceptibility is being detected. The synergistic effect of S.S.S. trubutyl phosphotritiade (DEF) and piperonil butoxide (PB) was analysed, and it was proven that esterases enzymes and multifunction oxidases are involved in the resistance to pyrethroids. By electrophoresis in polyerylamide gel, it was determined that the combination of esterases that seems to be associated with the resistance to perythroids is B1-A6-B6, which appeared with the greatest percentage. Valves of genetic frequency in the 6 municipalities were found to be high, for both esterase genes and acetylcholinesterase genes (Ache).

Animals↗
PubMed1994

Comparative distribution of neurotensin-like immunoreactivity in the brain of a teleost (Carassius auratus), an amphibian (Hyla meridionalis), and a reptile (Gallotia galloti).

The distribution of neurotensin (NT) was studied in the brain of three species belonging to the three major classes of cold-blooded vertebrates: teleost fishes (Carassius auratus), anuran amphibians (Hyla meridionalis), and reptiles (Gallotia galloti; Lacertidae). By using antibodies directed against synthetic bovine NT in the three species, immunoreactive cell bodies were discovered mostly in the telencephalon and diencephalon, in particular at the level of the preoptic region the mediobasal hypothalamus, and the thalamus. In the frog and the lizard, additional immunoreactive (ir) structures were observed in the optic tectum and the tegmentum of the mesencephalon. In the goldfish pituitary, an extensive innervation was consistently observed at the level of the rostral pars distalis, whereas in both frog and lizard, positive fibers were only detected in the external layer of the median eminence. In the three species there is a striking overlap between the distribution of the NT-ir cell bodies and that of the target cells for sexual steroids. The results are discussed in relation with those reported in birds and mammals, and with the possible interactions among NT, sexual steroids, and the neuroendocrine control of pituitary hormone release, in particular prolactin and gonadotrophin.

Amino Acid Sequence↗
PubMed1994

Cleavage of the NH2-terminal octapeptide of Bothrops asper myotoxic lysine-49 phospholipase A2 reduces its membrane-destabilizing effect.

Bothrops asper myotoxin II was cleaved with cyanogen bromide to determine the role of NH2-terminal amino acid residues in its ability to destabilize negatively charged liposomes and to induce myonecrosis. After treatment, cleaved toxin was separated from its NH2-terminal octapeptide by reversed-phase HPLC. Cleaved myotoxin II lost its capability to disrupt negatively charged liposomes, whereas it maintained approximately one-third of its muscle-damaging effect. No gross antigenic changes were detected after cleavage, as judged by immunoreactivity with polyclonal sera and a set of monoclonal antibodies. However, two of the tested MAbs showed a decreased binding to CB-myotoxin II. We conclude that the NH2-terminal octapeptide has an important role in the membrane-destabilizing activity of this toxin. This domain might directly participate in the binding of toxin to membranes, as well as in its pharmacological activities. Alternatively, conformational changes might occur in cleaved protein, altering its cytotoxic effects by indirectly modifying other important domains.

Animals↗
PubMed1994

The lacertidian reticular thalamic nucleus topographically upon the dorsal thalamus: experimental study in Gallotia galloti.

The projection pattern of the ventral thalamic reticular nucleus onto the dorsal thalamus was studied in the lizard Gallotia galloti using in vitro horseradish peroxidase and fluorescent carbocyanine labelling techniques. Localized label deposits at three dorsoventrally spaced sites in the dorsal thalamus elicited retrograde transport into separate, though partly overlapping, medial, dorsolateral and ventrolateral sectors within an extended cytoarchitectonic complex which may be globally identifiable as the reticular nucleus. Neurons found in the dorsolateral and ventrolateral sectors mainly corresponded to the cell group named nucleus ventromedialis (or nucleus of the dorsal supraoptic decussation) in the literature, whereas neurons labelled in the medial sector corresponded to the so-called dorsal hypothalamic nucleus. Sparser cells appear labelled in the superficially placed nucleus suprapeduncularis. Thalamotelencephalic fibers arising from the injected dorsal thalamic nuclei also project to the corresponding retrogradely labeled sectors within the reticular nucleus. These findings reveal a rough topographic organization in the connections of the extended reticular nucleus complex with the whole dorsal thalamus. This supports the hypothesis of hodological homology between this ventral thalamic formation in Gallotia and the mammalian thalamic reticular nucleus.

Animals↗
PubMed1994

Antigranulocyte bone marrow scans in Paget's disease.

Paget's disease of bone is a disorder of bone remodeling in which excessive production of structurally abnormal bone occurs, with the primary and fundamental abnormality residing in the osteoclast. To evaluate further the jeopardized bone marrow in Paget's disease, the authors studied 29 skeletal lesions by means of conventional bone imaging and antigranulocyte antibody bone marrow imaging in eight consecutive patients affected by Paget's disease. Bone scans showed abnormal tracer uptake in the 29 skeletal sites (11 pelves, 10 vertebrae, 5 extremities, 2 skulls, and 1 rib). Antigranulocyte antibody bone marrow scans showed decreased uptake of radiopharmaceutical in 16 (55%) of those 29 areas (8 pelves, 7 vertebrae, and 1 rib). Lesions appeared to be more extensive on bone scans than on bone marrow scans. It was concluded that antigranulocyte bone marrow scans may show focal defects in hematopoietic bone marrow in patients with Paget's disease. Paget's disease affects the cortical bone more severely than the bone marrow.

Aged↗
PubMed1994

[Treatment of metastatic prostatic cancer with monthly injections of leuprolide acetate depot].

Seventy-two patients were admitted in a multicentre trial with the purpose of assessing the clinical efficacy and safety of the hormonal control and tolerance of leuprolide acetate in a once-a-month depot injection formulation for the treatment of disseminated prostate cancer. During a 1-year follow-up, there were ten withdrawals for different reasons. At baseline and at 6 months of treatment the following parameters were evaluated: clinical examination, routine blood analysis, PAP, PSA, LH and testosterone, as well as bone scan. LH and testosterone determinations were repeated at 2, 4, 8, 12, 16, 20 and 24 weeks. Testosterone reached castration levels within the second week and was maintained until the end of the study. In agreement with the NPCP criteria, 65 patients were assessed as: complete response 3%, partial response 40%, disease stabilization 36%, and progression 21%. In summary, a once-a-month injection of leuprolide acetate offers a safe and effective alternative to surgical castration.

Adenocarcinoma↗
PubMed1994

[Resistance to organophosphate, carbamate, and pyrethroid insecticides in Blattella germanica (Dictyoptera: Blattellidae) in 2 municipalities of the City of Havana].

We determined the resistance of 2 Blattella germanica strains collected in 2 municipalities of City of Havana--Playa (P) and Centro Habana (CH)--to six insecticides: malathion, pyrimiphos-methyl, propoxur, cipermetrine, deltametrine, and lambda cialotrine. The P strain showed resistance only to deltametrine (FR = 80); the CH strain was susceptible to propoxur and lambda cialotrine and resistant to malathion (FR = 12), pyrimiphosmethyl (FR = 13), cipermetrine (FR = 16), and deltametrine (FR = 100). Gene frequency of increased esterases and of the modified acetylcholinesterase was determined in the 2 strains. The values of increased esterases in the two collected strains were: P = 0.90; and CH = 0.91. Values of the modified acetylcholinesterase in the two strains were: P = 0.47; and CH = 0.12.

Animals↗
PubMed1993

Immunohistochemical localization of transforming growth factor alpha in the developing rat colon.

BACKGROUND: Transforming growth factor alpha (TGF-alpha) is a 50-amino acid polypeptide that has been related to cell proliferation and differentiation. METHODS: Proximal and distal colon from fetal, newborn, and adult rats were studied by immunohistochemical techniques using a monoclonal antibody against human and rat TGF-alpha. RESULTS: Immunoreactive TGF-alpha (IR-TGF-alpha) first appeared in distal colon at 18 days of gestation when the proximal colon remained negative. At all ages studied, the staining for TGF-alpha at the base of the crypts in the distal colon showed a supranuclear pattern. At 22 days of gestation and until 9 days of postnatal development, the proximal colon is negative for TGF-alpha. From day 10 to 24 of postnatal development, IR TGF-alpha cells with a cytoplasmic staining were confined to the lower half of the villi. Afterwards, cells at the crypts showed supranuclear staining and cells in the surface epithelium a cytoplasmic reaction. CONCLUSIONS: Age- and region-dependent expression of TGF-alpha in the rat colon suggests a functional role for TGF-alpha in the establishment and maintenance of proliferation and differentiation during development.

Animals↗