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Biomedical subjects

R Castro

Publications and source records attributed to R Castro.

At least 73 records · Page 4Linked to original sources

[Effect of microcrystalline cellulose on the excretion of total biliary acids in feces].

The colorectal neoplasia is the second cause of death from neoplasia in our country, and in international statistics, blaming for this, the dietetic habits of industrialized countries having a high content of satured fat, cholesterol, refined carbohydrate, red meat, and with few dietetic fibers. In the last years special attention has been focused to the action of the total biliar acids (TBA) primarily the secondary ones, over the colon mucosa, showing evidences of cancerous effects. Recently, American authors have published the favoring action of the cellulose fiber over the TBA through a catalytic reaction and their polysterification, inactivating them in their aggressive action over the colon mucosa. Through these experiences and willing to prove the action of the product, we have treated with microcrystalline cellulosa (Microcel Lab. Blanver, Brasil) 20 patients of the Institute of Gastroenterology of Havana City, who showed high figures of TBA in stools for 2 months, compared with the 5 g. dose per day. Another group of 20 patients also with high figures of TBA in stools being treated with corn fecula same dose, same time by equal time, making every month determinations to both groups, determining that in the first group the figures of TBA in stools were normalized in 95% the first month of treatment and in 100% the second month. The second group had only an answer of 65% the first month and of 80% the second month, which shows evidently the high efficacy of Microcel in reducing the TBA in stools.

Adolescent↗

The subjective experience of health and illness in Ocuituco: a case study.

This sociological study aims to understand the subjective experience of health and illness of the inhabitants of Ocuituco (Mexico). This interpretation is made in connection with the social and subjective contexts of this town. Four factors characterize Ocuituco's social context: (1) economic deprivation (poverty); (2) male domination (patriarchy); (3) a process of medicalization; and (4) a decline of traditional medicine. Ocuitucans view their world (subjective context) with: (1) a sense of being exploited; (2) a sense of being at the bottom of the social scale; (3) a sense of uncertainty; (4) a familiarity with a patriarchal and violent order; (5) the negative view that individuals have of themselves; and (6) a sense of change in the community. The literature review differentiates between normative and interpretive sociological approaches. The analysis is based on 74 in-depth interviews with women and men, conducted in two stages (1988 and 1992). Individuals' accounts constitute a double indicator: they express individuals' subjective experience of health and illness while at the same time they also index the social order of which they are a product. The analysis comprises both the concept and the experience of health and illness. An analysis is made on the subjective experience of symptoms and causes of disease. The main findings refer to the parallel between individuals' general view of the world (subjective context) and their view of health and illness. Ocuitucans perceive health as an unlikely achievement in a world full of constraints. This is linked to the existence of elaborated conceptualizations of health in this town. The notion of strength is central in the subjective experience of illness.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Decreased surfactant dose-response after delayed administration to preterm rabbits.

Preterm rabbits from 14 litters were delivered at 27 d gestation, anesthetized, and treated with surfactant at birth, 15 min, or 30 min after the onset of mechanical ventilation. Doses of surfactant ranging from 0 to 100 mg/kg body weight were given intratracheally and the rabbits were ventilated for 45 min after birth. Pressure-volume curves and dynamic compliances demonstrated that the dose response to surfactant progressively decreased with delayed treatment. Following surfactant treatments of 50 mg/kg at birth, 15 min, and 30 min, peak lung volumes at 35 cm H2O were increased by 49, 30, and 8.4%, respectively over those of untreated controls. Lung lavages from rabbits receiving surfactant at 30 min had significantly higher protein contents and minimum surface tensions on the Wilhelmy balance than those from rabbits treated at birth (23.1 +/- 1.1 versus 16.0 +/- 2.7 dynes/cm), and lung sections from rabbits treated at 30 min had a significantly less uniform distribution of surfactant than those from rabbits treated at birth. While increasing phospholipid concentrations may reverse the inhibition of surfactant by serum proteins in vitro, there was a progressive inability of exogenous surfactant to overcome this inhibition in vivo following delayed administration to very immature rabbits. This inability to overcome inhibition with increasing surfactant dose was associated with a less uniform distribution of surfactant following its delayed administration.

Animals↗

Cognitive sequelae of treatment in childhood acute lymphoblastic leukemia: cranial radiation requires an accomplice.

PURPOSE: We evaluated cognitive sequelae of treatment for childhood acute lymphoblastic leukemia (ALL). CNS therapy consisted of cranial irradiation (CRT) or no radiation. Children were also randomized to single intravenous high-dose methotrexate (HD-MTX) or conventional-dose methotrexate (CD-MTX) during induction, and all patients received intrathecal (IT) and systemic continuation chemotherapy. PATIENTS AND METHODS: Sixty-six patients treated for ALL on Dana-Farber Cancer Institute protocol 87-01 were evaluated by standardized cognitive and achievement tests. These children had been assigned at diagnosis to a standard-risk (SR) or high-risk (HR) group and received no CRT or 18 Gy CRT, respectively. All patients were randomized to receive MTX during remission induction, either as CD-MTX (40 mg/m2) or HD-MTX (4 g/m2) with leucovorin rescue. RESULTS: There was no difference in cognitive outcomes between radiated and unirradiated patients (P > .4). However, the HD-MTX/CRT combination was associated with decreased intelligence quotient (IQ estimate, 9.3 points) for girls only (P < .08). A specific deficit in verbal coding and memory was documented for all patients (P < .0001). CONCLUSION: We conclude the following: (1) 18 Gy CRT per se was not an independent toxic agent for cognitive outcome; (2) HD-MTX during induction was associated with IQ decline in girls, but only when it was followed by CRT; and (3) impairment of verbal memory and coding was a consistent finding that was independent of CRT, which implicates some component of chemotherapy, possibly prednisone, as a CNS toxin.

Analysis of Variance↗

[Breast feeding and the nutritional status of Chilean children].

The purpose of this work was to describe the diet of children under 18 months of age and its relationship to nutritional status. For this purpose, in 1993 a prevalence study was carried out on children who received care from the National Health Services System of Chile. The Chilean public health system provides care to 75% of children under 6 years of age and especially to children of families in the lower strata of income distribution in the country. Participants in the study were 9330 children under 18 months old who were randomly selected from 102 of the 320 urban clinics throughout the country. The type of food these infants had received the day prior to the interview (breast milk exclusively, breast milk plus solid food, formula exclusively, formula plus solid food) and their nutritional status relative to the standards of the National Center for Health Statistics (United States of America) and of WHO were determined. Children with z values for weight-for-age between -1.0 and -2.0 standard deviations were considered at risk for malnutrition, and those with z values under 2 standard deviations were classified as malnourished. The prevalences of exclusive breast-feeding at the first, third, and sixth months of life were 86.5%, 66.7%, and 25.3%, respectively. Some 12.1% of the participants showed low weight for age; 30.7%, low height for age; and 35.7%, overweight. The magnitude of weight-for-age deficiency was 1.2 to 5 times greater among children who were fed milk substitutes than among those who received breast milk. Breast-feeding also had a positive effect on height. These results confirm the benefits of exclusive breast-feeding until 6 months of age, the need to supplement the child's diet with solid food after that age, and the breast-feeding's protective effect on the nutritional status of children of all the ages studied.

Body Height↗

[Malnutrition of the pregnant woman: an overestimated problem?].

The aim of this work was to compare the nutritional classification of pregnant women and their predictive value for low birth weight, using the criteria of the Ministry of Health (Rosso-Mardones curves) with the curves developed at the Department of Nutrition of the Faculty of Medicine and the body mass index. One thousand eight hundred four pregnant women of the Metropolitan Region, that were devoid of factors affecting birth weight, were studied retrospectively. Initial and final nutritional status was calculated according to the three criteria in study. Results showed that 47 to 75% of women classified as undernourished using Rosso-Mardones curves, were normal according to the curves of the Department of Nutrition and body mass index. Rosso-Mardones curves had the lower predictive value, relative risk and risk attributable to maternal nutritional deficit, for low birth weight. Also these curves showed a higher of obesity and a low predictive value for macrosomia. It is concluded that the curves used by the Ministry of Health must be revised.

Birth Weight↗

From research to public health interventions. I. Impact of an educational strategy for physicians to improve treatment practices of common diseases.

Errors in treating common diseases occur very frequently in primary health care practice. While many of these mistakes are not life-threatening, the costs of abuse in drug prescription may be greatly increased. An educational strategy aimed to improve physicians' prescribing practices for acute diarrhea (AD) and acute respiratory infection (ARI) was developed as a research study, involving three medical care units. The strategy was largely based on promoting active participation of the trainees in the whole process, including: (a) group participation in a literature review of updated articles related to management of AD and ARI; (b) analysis of prescribing practices before the intervention; (c) participation in the development of a clinical algorithm for the therapeutic management of these illnesses; and (d) discussion of the usefulness of the algorithm during peer review committee meetings. Successful results of this intervention, as judged by the improvement of treatment practices and the persistence of changes for up to 2 years after the intervention, as well as its ease of application and low costs, motivated its extension to a health District and a State. In these sites, the intervention was in charge of medical leaders from the clinics and medical heads of the local health systems, respectively. The extension of the educational strategy was accompanied by a relative reduction in AD from 46.7% to 6.5% and in ARI from 32.6% to 8.5%. However, the benefit-cost ratio showed a dramatic increase when comparing results from the research study and from the State intervention, for both AD (from 3.3 to 4.4) and ARI (from 16.2 to 21.6), for an overall net increase of 33.3%. Based on these results, the educational strategy was adopted by the National Program for the Control of Diarrheal Diseases, and was used to train public health physicians throughout the country, from 1992 to 1994.

Acute Disease↗

Functional expression of human poly(ADP-ribose) polymerase in Schizosaccharomyces pombe results in mitotic delay at G1, increased mutation rate, and sensitization to radiation.

The activity of poly(ADP-ribose) polymerase (PADPRP), a chromatin-associated enzyme present in most eukaryotic cells, is stimulated by DNA strand breaks, suggesting a role for the enzyme in the cellular response to DNA damage. However, the primary function of PADPRP remains unknown. We have selected Schizosaccharomyces pombe as a simple eukaryotic system in which to study PADPRP function because this fission yeast shares with mammalian cells important cellular features possibly associated with poly-(ADP-ribos)ylation pathways. We investigated the existence of an endogenous yeast PADPRP by DNA and RNA hybridization to mammalian probes under low-stringency conditions and by PADPRP activity assays. Our data indicate that fission yeasts are naturally devoid of PADPRP. We therefore isolated S. pombe strains expressing PADPRP by transformation with a human full-length PADPRP cDNA under the control of the SV40 early promoter. The human PADPRP construct was transcribed and translated in S. pombe, generating a major transcript of the same size (3.7 kb) as that detected in mammalian cells and a 113-kDa polypeptide, identical in size to the native human PADPRP protein. Yeast recombinant PADPRP was enzymatically active and was recognized by antibodies to human PADPRP. S. pombe cells expressing PADPRP (SPT strains) showed a stable phenotype that was characterized by: (i) cell cycle retardation as a result of a specific delay at the G1 phase, (ii) decreased cell viability in stationary cultures, (iii) enhanced rates of spontaneous and radiation-induced ade6-ade7 mutations, and (iv) increased sensitivity to radiation. SPT strains may prove efficient tools with which to investigate PADPRP functions in eukaryotic cells.

Dose-Response Relationship, Radiation↗

Prenatal haloperidol induces a selective reduction in the expression of plasticity-related genes in neonate rat forebrain.

Haloperidol, a dopamine receptor antagonist clinically used as an antipsychotic drug, induces long-term deleterious effects in offspring development when administered prenatally. However, the basis for this overall response to the drug remains unknown. Here we describe that prenatal administration of haloperidol in rats induces a drastic and selective reduction in the expression of plasticity-related genes in neonate forebrain, but not in mesencephalon. GABAergic and enkephalinergic markers such as glutamic acid decarboxylase activity and mRNA, and preproenkephalin mRNA were also diminished in forebrain. However, the expression of other genes such as epidermal growth factor-receptor, glial fibrillary acidic protein, and several proto-oncogenes (src, fos and myc), and a cholinergic marker such as choline acetyltransferase activity were unaltered. In addition, haloperidol promoted a significant decrease in mitotic cell number and cellular density in the striatum, one of the forebrain regions with the highest dopamine receptor density. These findings suggest that prenatal dopamine receptor occupancy may be a critical factor in controlling the development of forebrain target cells through mechanisms involving changes in the expression of plasticity-related genes.

Actins↗

Genotoxicity testing of different types of beverages in the Drosophila wing Somatic Mutation And Recombination Test.

Five wines and one brandy of Spanish origin as well as three herbal teas and ordinary black tea were tested for genotoxicity in the wing Somatic Mutation And Recombination Test (SMART) which makes use of the two recessive wing cell markers multiple wing hairs (mwh) and flare (flr3) on the left arm of chromosome 3 of Drosophila melanogaster. 3-day-old larvae trans-heterozygous for these two markers were fed the beverages at different concentrations and for different feeding periods using Drosophila instant medium. Somatic mutations or mitotic recombinations induced in the cells of the wing imaginal discs give rise to mutant single or twin spots on the wing blade of the emerging adult flies showing either the mwh phenotype or/and the flr phenotype. One of the red wines showed a clear genotoxic activity that was not due to its ethanol content. Two herbal teas (Urtica dioica, Achillea millefolium) and black tea (Camellia sinensis) proved to be weakly genotoxic as well. Furthermore, it was shown that quercetin and rutin, two flavonols present in beverages of plant origin, also exhibited weak genotoxic activity in the somatic cells of Drosophila. These results demonstrate that Drosophila in vivo somatic assays can detect the genotoxicity of complex mixtures such as beverages. In particular, it is possible to administer these test materials in the same form as that in which they are normally consumed.

Alcoholic Beverages↗

Characterization of T-helper epitopes of the glycoprotein of vesicular stomatitis virus.

The T-helper (Th) cell epitopes in the glycoprotein (GP) of vesicular stomatitis virus serotype Indiana (VSV-IND) were analyzed with a complete panel of overlapping synthetic peptides. Three Th-cell epitopes in C57BL/6 (H-2b) mice and two epitopes in BALB/c (H-2d) mice were defined by their ability to stimulate in vitro proliferation of virus-primed, CD8+ T-cell-depleted spleen cells in a class II-restricted manner. A series of CD4+, I-Ab-restricted T-cell hybridomas from VSV-primed C57BL/6 mice were characterized by their production of interleukin-2 and interleukin-3 upon stimulation with VSV-IND or purified VSV GP in vitro. Of nine hybridomas derived from three independent fusions, five were specific for amino acids (aa) 415 to 433 (p8) of VSV-IND GP, three recognized aa 52 to 71 (p41), and one reacted against aa 316 to 335 (p17). Fluorocytometric analysis of Th hybridomas or VSV-stimulated T-cell lines with monoclonal antibodies specific for the T-cell receptor V beta chain did not reveal obvious correlations between the T-cell receptor V beta gene segment used and the epitope recognized. All three peptides recognized by H-2b mice and both epitopes recognized by H-2d mice which were characterized in primed T-cell populations were capable of activating specific Th cells in vivo as measured by the induction of antibody class switch from immunoglobulin M (IgM) to IgG. Thus, the epitopes are relevant for VSV GP-specific Th response in vivo and are able to provide functional help for the production of anti-VSV-specific neutralizing IgG antibodies.

Amino Acid Sequence↗

Vascular effects alter early-gestation fetal renal responses to vasopressin.

Distinct receptors mediate the vascular (V1) and renal (V2) effects of arginine vasopressin (AVP). Although ovine fetal AVP-induced antidiuresis can be demonstrated in early gestation (< 120 days; term 150 days), the early-gestation fetal renal responses to AVP are variable, including increases in urine flow and glomerular filtration rate (GFR). AVP V1 receptor predominance and/or V2 receptor system immaturity may contribute to variable early-gestation renal responses to AVP. To differentiate these possibilities, we assessed early-gestation fetal V2 receptor function in the presence and absence of V1 receptor-mediated effects by comparing the responses to AVP (a combined V1-V2 receptor agonist; n = 10; 112 +/- 2 days) with the selective V2-receptor agonist 1-desamino-8-D-arginine vasopressin (DDAVP) (n = 5; 111 +/- 2 days). AVP infusion increased fetal mean arterial pressure (MAP; 36 +/- 1 to 44 +/- 2 mmHg) and decreased heart rate (197 +/- 2 to 171 +/- 3 beats/min); DDAVP infusion had no effect on MAP or heart rate. Free water clearance decreased in response to AVP (0.13 +/- 0.02 to 0.02 +/- 0.01 ml.min-1.kg-1) and DDAVP (0.21 +/- 0.04 to 0.04 +/- 0.02 ml.min-1.kg-1), and urine osmolality increased in response to both analogues (AVP: 145 +/- 4 to 283 +/- 15 mosmol/kgH2O; DDAVP: 146 +/- 5 to 244 +/- 32 mosmol/kgH2O).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

cph, a novel oncogene which cooperates with H-ras in the transformation of NIH3T3 fibroblasts.

We have performed the molecular cloning of the non-ras transforming sequences previously detected in neoplastic Syrian hamster embryo fibroblasts initiated in vitro with 3-methylcholanthrene (MCA) (Notario et al., 1990). These sequences were isolated using cosmid-rescue techniques from a third-cycle NIH3T3 transformant obtained by sequential transfections of genomic DNA from MCA-initiated hamster fetal cells. Rescued (C-5) clones encompassed about 42.5 kbp of Syrian hamster genomic DNA containing hamster-specific repetitive elements (HRS). An internal 19 kbp BamHI fragment (B-1) was the only C-5 fragment which recognized specific transcripts in poly(A)+ RNA from hamster embryo cells. The same mRNA species were present in both normal and MCA-initiated neoplastic cells: a major transcript of about 2.5 kb, and other less abundant ones, ranging from approximately 2.0 kb to 5.0 kb. These mRNA species were detected consistently by each of several B-1 DNA subfragments located at positions spanning almost the entire B-1 length. The nucleotide sequence of some transcript-positive (S5P2 and S6) genomic B-1 fragments was determined. No significant homology exists between the nucleotide sequences of these B-1 subfragments and established DNA databases. Therefore, the C-5 cosmid clone contains novel genomic sequences. Transfection of C-5 DNA into mouse NIH3T3 cells resulted in the appearance of transformed foci (about five foci per microgram of DNA) within 25 days post-transfection, thus demonstrating the transforming activity of the C-5 clone, which was consequently renamed as the cph oncogene. Co-transfection of the cph oncogene with the human H-ras oncogene (T24), demonstrated a synergistic action between the two oncogenes in the transformation of murine fibroblasts.

3T3 Cells↗

Cytokines as adjuvants: effect on the immunogenicity of NeuAc alpha 2-6GalNAc alpha-O-Ser/Thr (sialyl-Tn).

Sialyl-Tn, defined by monoclonal antibody (MAb) B72.3, shows restricted normal-tissue distribution but is expressed in a wide variety of carcinomas. To analyze the immunogenicity of sialyl-Tn, mice were immunized with ovine submaxillary mucin (OSM) in combination with monophosphoryl lipid A (MPLA), liposomes, or adjuvants that activate macrophages (rIL-1, rIFN-gamma, rM-CSF, IL-1-derived peptides) or T cells (rIL-2). The level and specificity of the immune response were analyzed by ELISA. rIL-1 and rIFN-gamma induced a very high and specific antibody response, whereas the effect of rM-CSF was dose-dependent: at a low dose it induced a high-level specific antibody response and at the high dose level it induced a polyclonal non-specific response. These results indicate that cytokines are powerful adjuvants which modulate both the magnitude and specificity of the immune response. More studies are necessary to determine the optimal doses in animal models and in active specific immunotherapy of patients with cancer.

Adjuvants, Immunologic↗

Variant cysteine-rich surface proteins of Giardia isolates from human and animal sources.

Cloned Giardia isolates obtained from a sheep, a calf, and a human possessed a major membrane protein that showed marked intraspecific variations in size as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis following surface biotinylation and radioiodination. Metabolic labeling with [35S] cysteine and electrophoretic analysis also revealed for each cloned isolate a predominant protein that corresponded in size to the major surface protein demonstrated by surface labeling techniques. Immunoprecipitation studies with a polyclonal antiserum specifically directed against the 90-kDa major cysteine-rich protein purified from a subclone of the sheep isolate (O2-4A1) showed that the cysteine-rich protein and the major surface protein are identical. The surface location of the antigen was further corroborated by the reaction of fluorescence-labeled antibodies raised against the 90-kDa O2-4A1 cysteine-rich protein with the entire surface of live trophozoites of the homologous clone. The ability of the cloned Giardia isolates to undergo variations of their cysteine-rich surface protein (CRISP) was demonstrated by the spontaneous appearance of new CRISPs in clonally derived populations during prolonged in vitro culturing and in cultures of the O2-4A1 clone that had survived treatment with the cytotoxic anti-90-kDa CRISP antiserum specific for the surface antigen of this clone. The surviving progeny were devoid of the original CRISP, as judged by resistance to the immune serum. Subsequent cysteine metabolic labeling of the recloned surviving trophozoites demonstrated a large number of new variants, each expressing a single CRISP that varied significantly in molecular weight from those in the different cloned lines. These studies suggest that the presence of CRISPs and their variations are not restricted to Giardia isolates obtained from humans but are universal phenomena among the Giardia duodenalis types of organisms.

Animals↗

[Evaluation of regression of left ventricular hypertrophy after antihypertensive therapy. Comparative echo-Doppler study of ace inhibitors and calcium antagonists].

This study evaluates 33 patients suffering from mild-moderate arterial hypertension (systolic blood pressure over 160 mmHg; diastolic blood pressure over 95 mmHg) and with concomitant indications of concentric left ventricular hypertrophy at echocardiography. Twenty patients completed the trial according to the criteria established in the protocol and were found suitable for evaluation of the results at the end of the study. Ten patients were treated with 40 mg of nifedipine retard tablets, administered twice (1 x 20 mg tablet twice daily) and 10 patients were treated with a single administration of 20 mg quinapril (1 x 20 mg tablet per day). Total follow-up was performed for one year (variability 12-14 months) with evaluation of the pressure response at 1-3-6-12 months and clinical evaluation and echocardiographic control for comparison with the baseline at the end of the study. The left ventricular mass values measured at the end of the study presented a statistically significant reduction (p < 0.001) with respect to the baseline in both groups. In the patients treated with quinapril the percentage regression of left ventricular hypertrophy was 19.39%, and slightly higher (19.5%) in the patients treated with nifedipine. Finally, although the series is perhaps too limited to draw conclusions, the finding that the indicators of diastolic filling of the left ventricle improved, and, in particular, were correlated with an increase in the speed of the first fast filling phase, and thus that there was a partial improvement in left ventricular compliance, is important.

Adult↗

Ovine maternal and fetal glomerular atrial natriuretic factor receptors: response to dehydration.

In pregnancy, dehydration produces marked effects on maternal and fetal body water homeostasis including an increase in fetal urinary sodium concentration and excretion. To examine the role of fetal plasma atrial natriuretic factor (ANF) and glomerular ANF receptors in dehydration-induced natriuresis, we compared plasma ANF levels and glomerular ANF binding characteristics in dehydrated and control maternal and fetal sheep. Mean (+/- SEM) maternal and fetal plasma ANF levels in control animals (n = 9) at 132-136 days gestation were 37 +/- 3 pg/ml and 138 +/- 20 pg/ml, respectively. Although mean ANF receptor maximum binding capacities (Bmax) were significantly higher in maternal than in fetal glomeruli (83 +/- 11 vs 34 +/- 12 fmol/mg protein, respectively), the dissociation constants (Kd) for ANF binding were not different (2.7 +/- 0.6 and 3.7 +/- 1.7 x 10(-10) M, respectively). In an additional 9 animals studied after 63 +/- 4 h of water deprivation, maternal plasma ANF levels were significantly lower than in the control group (14 +/- 4 vs. 37 +/- 3 pg/ml), maternal glomerular ANF receptor Bmax values were significantly higher (732 +/- 203 vs. 83 +/- 11 fmol/mg protein), and Kd values were six-fold higher (17.0 +/- 7.1 vs. 2.7 +/- 0.6 x 10(-10) M), although this difference was only marginally significant (p = 0.06). In contrast to the adult, there was a small, nonsignificant decrease in plasma ANF levels and no difference in Bmax or Kd values between the dehydrated and euhydrated fetal animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗