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E Estrada

Publications and source records attributed to E Estrada.

53 records · Page 3Linked to original sources
PubMed1984

Regional distribution of neurotransmitter receptors in the visual structures of the rat brain.

The regional distribution of the binding of 3H-quinuclidinyl benzylate, 3H-dihydroergocryptine, 3H-dihydroalprenolol, 3H-serotonin and 3H-flunitrazepam was investigated in the retina, lateral geniculate nucleus, superior colliculus, visual and frontal cortex of 25-day-old and adult rats. In adult rats the highest binding levels for the muscarinic acetylcholine and benzodiazepine receptor are present in the visual and frontal cortex, whereas alpha- and beta-adrenergic receptor binding was highest in the retina and 3H-serotonin binding in the lateral geniculate nucleus. Binding of 3H-quinuclidinyl benzylate, 3H-flunitrazepam and 3H-serotonin increases in the adult rats, whereas alpha- and beta-adrenergic receptor binding is decreased compared to the binding levels found in 25-day-old animals. The distribution of the neurotransmitter receptors studied within the visual structures cannot be readily correlated with the pattern of some neurochemical presynaptic parameters.

Animals↗
PubMed1984

Phase I trial of intermittent high-dose dacarbazine.

A phase I study was conducted with dacarbazine (DTIC) protected from light and administered iv as a single dose every 3 weeks. Eighteen patients received 47 courses of DTIC, with doses ranging from 850 to 1980 mg/m2. Hypotension was the dose-limiting toxic effect and it may be secondary to the citric acid present in the pharmaceutic preparation of DTIC. Sporadic myelosuppression was seen at doses greater than 1380 mg/m2. Other side effects noted were nausea and vomiting, acute diarrhea, headache, a "flu-like" syndrome, and a hypersensitivity reaction to sunlight. No antitumor activity was found. The results of this study indicate that this may be a qualitatively different way of giving DTIC, and that the side effects of this drug may be intermingled with those of citric acid in this particular schedule. If the conventional pharmaceutic preparation of this drug is not modified, further studies with high-dose DTIC protected from light should be discouraged.

Adult↗
PubMed1982

The effect of increased CSF pressure on interstitial fluid flow during ventriculocisternal perfusion in the cat.

Transependymal absorption of cerebrospinal fluid (CSF) in hydrocephalus is suggested by periventricular edema, but the necessary bulk flow of interstitial fluid (ISF) has not been found. We performed ventriculocisternal perfusions in adult cats using CSF with the extracellular marker [3H]sucrose. CSF pressure was maintained at -5(control), 20 or 40 cm H2O for 2 or 4 h. Some animals had perfusions with isotope for the full experiment while others had an isotope-free perfusion for 2 h followed by a delayed-pulse with isotope. Apparent diffusion coefficients and distribution spaces for sucrose were determined from depth of isotope penetration. White matter apparent diffusion coefficients were statistically increased compared to controls for the 4-h 20 cm H2O and 2-h 40 cm H2O experiments. Apparent diffusion coefficients for delayed-pulse experiments at increased pressure were greater than those of full-pulse. Sucrose distribution spaces were not enlarged at the various pressures. Alteration of ISF transport in periventricular white matter occurred with increased pressure. These time-dependent changes in bulk flow rate indicate either a decrease in normal ISF flow toward the ventricle or reversal of transependymal ISF flow.

Animals↗
PubMed1980

Bulk flow of brain interstitial fluid under normal and hyperosmolar conditions.

Although bulk flow of brain interstitial fluid (ISF) occurs with changes in hydrostatic and osmotic pressures, under normal conditions only diffusion of molecules in the ISF has been reported. Extrachoroidal cerebrospinal fluid (CSF) production and intracerebral injection studies, however, provide indirect evidence for the bulk flow of ISF under normal conditions. We studied tissue penetration profiles of an extracellular molecule in gray and white matter after 1-, 2-, 3-, and 4-h ventriculocisternal perfusions. Gray matter apparent diffusion coefficients were similar at different times as expected with diffusion; however, white matter coefficients decreased significantly with time, suggesting bulk flow of ISF. White matter data was reanalyzed for both bulk flow and diffusion; we calculated a diffusion coefficient of 3.00 x 10(-6) cm2/s and a velocity for ISF of 10.5 micrometers/min toward the ventricle. Additional animals were given 20% mannitol (1.5--3 g/kg) intravenously prior to a /-h ventriculocisternal perfusion. Mannitol produced a significant bulk flow of ISF away from the ventricle in gray matter. We estimate that 30% of extrachoroidal CSF production is from flow of ISF in white matter.

Animals↗
PubMed1978

[Uptake of tryptophan and tyrosine in some cases of manic depressive psychosis and schizophrenia (author's transl)].

The uptake of tryptophan and tyrosine by the brain has been studied in 6 manic-depressive patients and in 8 schizophrenics. In an attempt to saturate the blood-brain transport mechanisms, this uptake has been evaluated by measuring the arteriovenous differences (arterial plasma-internal jugular plasma) of these two amino acids before and after perfusion with L-dopa and L-5-HTP. Considering a positive difference as an uptake and a negative one as an outflow, results show (1) in melancholia an uptake of tryptophan and an outflow of tyrosine; (2) in mania an uptake of tyrosine and an outflow of tryptophan, and (3) in schizophrenia an outflow of tryptophan accompanied with either an uptake or an outflow of tyrosine. In addition, the kinetics of tryptophan binding to plasma proteins and the ratio of tryptophan/tyrosine uptake are different in manic-depressive illness and in schizophrenia. These results support the view that a disturbance in the blood-brain transport mechanisms of tryptophan and tyrosine could be involved in the physiopathology of manic-depressive illness and schizophrenia.

Bipolar Disorder↗
PubMed1976

[Coffee hulls and pulp. XII. Effect of storage of coffee pulp on its nutritive value for calves].

Coffee pulp, dehydrated and stored for 7, 13 and 17 months or ensiled for 4, 10 and 14 months, was studied in calves with a rapid growing rate. Storage of dehydrated coffee pulp did not affect its chemical composition, but ensiling reduced crude fiber and increased its nitrogen free extract content after 10 and 14 months. Three growth trials were carried out with Holstein calves averaging 95 kg in the first and second trials, and 130 kg in the third. Eighteen calves were used in the first trial and 24 in each of the other two. In each trial the animals were divided into three equal groups and randomly assigned to one of the following treatments: control, which contained 48% cottonseed hulls, and the other two, with 30% dehydrated coffee pulp or 30% ensiled coffee pulp. Basically, the difference between trials consisted in the time of storage or ensiling of coffee pulp. In all trials, weight gains of calves fed coffee pulp (1.00, 0.90 and 0.98 kg/day, and 1.06, 0.94 and 1.08 kg/day, respectively) were significantly lower (P less than 0.05) than the weight gains induced by the control ration (1.21, 1.08 and 1.19 kg/day). Feed intake was also lower, but feed conversion ratio was higher for those rations containing coffee pulp. Calf performance was better with ensiled than with deydrated coffee pulp, particularly in the third trial, where the differences in weight gains were significantly higher (P less than 0.05). It is concluded that storage time does not change nutritive value of coffee pulp; and the ensiling is an adequate process for storing pulp during coffee harvesting, and, possibly also, for improving its nutritive value.

Animal Feed↗
PubMedDate not supplied

Modeling diamagnetic and magnetooptic properties of organic compounds with the TOSS-MODE approach.

The topological substructural molecular design (TOSS-MODE) approach is used to describe the diamagnetic susceptibility of organic compounds. Two data sets composed of 233 aliphatic and 85 aromatic compounds were studied for which good linear correlations were found. The contributions of many different structural fragments and atomic groups were computed by the current approach. The predictive ability of the models developed was tested by using external prediction sets of compounds of different classes than those used in training. A quantitative model based on the current approach was developed to compute the diamagnetic susceptibility exaltation of aromatic compounds, which is exemplified by the study of polycyclic aromatic hydrocarbons. The rotatory power of organic compounds in a magnetic field was also described by the TOSS-MODE approach. Good linear correlations were obtained for this property in aliphatic and aromatic compounds. The predictive abilities of the models found were tested by external prediction sets for which good correlations between calculated and experimental values are found.

Journal Article↗
PubMedDate not supplied

3D connectivity indices in QSPR/QSAR studies.

Topographic (3D) molecular connectivity indices based on molecular graphs weighted with quantum chemical parameters are used in QSPR and QSAR studies. These descriptors were compared to 2D connectivity indices (vertex and edge ones) and to quantum chemical descriptors in modeling partition coefficient (log P) and antibacterial activity of 2-furylethylene derivatives. In describing log P the 3D connectivity indices produced a significant improvement (more than 29%) in the predictive capacity of the model compared to those derived with topological and quantum chemical descriptors. The best linear discriminant model for classifying antibacterial activity of these compounds was also obtained with the use of 3D connectivity indices. The global percent of good classification obtained with 3D and 2D connectivity as well as quantum chemical descriptors were 94.1, 91.2, and 88.2, respectively. In general, all these models predict correctly the antibacterial activity of a set of nine new 2-furylethylene derivatives. The best result is obtained with 3D connectivity indices that classified correctly 100% of these compounds versus 88.9% obtained with 2D connectivity or quantum chemical descriptors.

Journal Article↗
PubMedDate not supplied

Can 3D structural parameters be predicted from 2D (topological) molecular descriptors?

The dihedral angle between both phenyl rings determined by photoelectron spectroscopy in a series of seven alkylbiphenyl is described by the local spectral moments of the bond matrix. This series is extended to 78 alkylbiphenyl compounds by estimating the dihedral angle from molecular mechanics force field calculations. The linear correlation obtained between this angle and the local spectral moments shown a correlation coefficient of 0.9838. This result proves that 2D (topological) descriptors can account for 3D structural parameters. A new substituent constant is calculated as the contribution of groups to the studied rotational angle by using the information encoded into the local spectral moments. This substituent constant is not linearly related to the Taft's steric constants E(S) as they have a correlation coefficient of only 0.75. These steric constants are able to account only for 71% of the variance in the studied 3D parameter. The implications for QSPR/QSAR studies of the demonstration that 2D (topological) descriptors can describe 3D structural parameters are also analyzed.

Journal Article↗
PubMedDate not supplied

Combination of 2D-, 3D-connectivity and quantum chemical descriptors in QSPR. Complexation of alpha- and beta-cyclodextrin with benzene derivatives.

Quantitative models are found to describe the complexation of alpha- and beta-cyclodextrin with mono- and 1,4-disubstituted benzene derivatives by using combinations of 2D-, 3D-connectivity and quantum chemical molecular descriptors. The association constants (K(a)) for the inclusion complexation of cyclodextrins and benzene derivatives are calculated by the models found with a high degree of precision. These models also permit the interpretation of the driving forces of such complexation processes. In the case of the complexation of alpha-cyclodextrin with benzene derivatives these driving forces are mainly the electronic repulsion between frontier orbitals of the host and guest molecules. However, the complexation of beta-cyclodextrin with benzene derivatives is controlled by topological and topographic parameters indicating the relevance of the van der Waals and hydrophobic interactions. We also carried out molecular modeling studies showing that for alpha-cyclodextrin complexes the benzene ring is outside the cavity of the cyclodextrin, while in beta-cyclodextrin they penetrate deeply into the apolar and hydrophobic cavity of the host, which explain the differences in the driving forces for both complexation processes.

Journal Article↗
PubMedDate not supplied

Combination chemotherapy with cisplatin and 5-fluorouracil 5-day infusion in the therapy of advanced gastric cancer: a phase II trial.

Fifty-six patients with measurable or evaluable advanced gastric cancer were treated with cisplatin, 100 mg/m2 in continuous infusion of 24 hours, and 5-fluorouracil, 1000 mg/m2/day (by continuous 5-day infusion) every 4 weeks. Three patients were found ineligible for the study. A response rate of 41% (22/53) was obtained (95% confidence interval: 28%-54%), with a median duration of remission of 10.2 months and an overall median survival time of 10.6 months. Leukopenia and thrombocytopenia were mild. Nausea and vomiting were common, and 23.5% of the patients had grade 3 stomatitis. Peripheral neuropathy and renal insufficiency increased with the number of cycles, representing the cumulative dose-limiting toxicity. This study indicates that the combination of cisplatin plus 5-fluorouracil is synergistic or at least has additive antitumor activity. We think that this association of 2 drugs should be considered for further phase III clinical trials.

Adult↗
PubMedDate not supplied

Ranking of hair dye substances according to predicted sensitization potency: quantitative structure-activity relationships.

Allergic contact dermatitis following the use of hair dyes is well known. Many chemicals are used in hair dyes and it is unlikely that all cases of hair dye allergy can be diagnosed by means of patch testing with p-phenylenediamine (PPD). The objectives of this study are to identify all hair dye substances registered in Europe and to provide their tonnage data. The sensitization potential of each substance was then estimated by using a quantitative structure-activity relationship (QSAR) model and the substances were ranked according to their predicted potency. A cluster analysis was performed in order to help select a number of chemically diverse hair dye substances that could be used in subsequent clinical work. Various information sources, including the Inventory of Cosmetics Ingredients, new regulations on cosmetics, data on total use and ChemId (the Chemical Search Input website provided by the National Library of Medicine), were used in order to identify the names and structures of the hair dyes. A QSAR model, developed with the help of experimental local lymph node assay data and topological sub-structural molecular descriptors (TOPS-MODE), was used in order to predict the likely sensitization potential. Predictions for sensitization potential were made for the 229 substances that could be identified by means of a chemical structure, the majority of these hair dyes (75%) being predicted to be strong/moderate sensitizers. Only 22% were predicted to be weak sensitizers and 3% were predicted to be extremely weak or non-sensitizing. Eight of the most widely used hair dye substances were predicted to be strong/moderate sensitizers, including PPD - which is the most commonly used hair dye allergy marker in patch testing. A cluster analysis by using TOPS-MODE descriptors as inputs helped us group the hair dye substances according to their chemical similarity. This would facilitate the selection of potential substances for clinical patch testing. A patch-test series with potent, frequently used, substances representing various chemical clusters is suggested. This may prove useful in diagnosing PPD-negative patients with symptoms of hair dye allergy and would provide some clinical validation of the QSAR predictions.

Allergens↗
PubMedDate not supplied

Breastfeeding support services in the neonatal intensive-care unit.

OBJECTIVE: To describe a model for providing breastfeeding support in the neonatal intensive-care unit (NICU). DESIGN: Naturalistic, participant observation. SETTING: Suburban Level III NICU. PATIENTS: One hundred thirty-two mother-infant pairs over 1 year. Infants were hospitalized in the NICU, and mothers had initiated lactation efforts. INTERVENTIONS: Investigators provided breastfeeding interventions for the mother-infant pairs, based on identified problems, the research literature, or both. MAIN OUTCOME MEASURES: Percentage of mothers who were breastfeeding at the time of discharge from the NICU. RESULT: Interventions were classified into five categories: expression and collection of mothers' milk, gavage feeding of expressed mothers' milk, in-hospital breastfeeding sessions, postdischarge breastfeeding management, and additional consultation. CONCLUSIONS: This model was effective in preventing breastfeeding failure for this population. The model can provide the basis for NICU breastfeeding standards of care, protocols, and chart records, or for reimbursement purposes. The model also provides a framework for studying a specific category or breastfeeding intervention.

Aftercare↗
PubMedDate not supplied

[Ewing's sarcoma].

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Child, Preschool↗