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Biomedical subjects

S Castro

Publications and source records attributed to S Castro.

At least 37 records · Page 2Linked to original sources
PubMed1996

2,4-Dichlorophenoxyacetic acid affects the attachment of Azospirillum brasilense Cd to maize roots.

2.4-Dichlorophenoxyacetic acid (2,4-D) is a herbicide widely applied to forage, grain and cereals. We previously determined that 1 mM 2,4-D diminished cell growth and cellular activity of Azospirillum brasilense Cd. The present work was designed to determine the possible effect of this herbicide--at concentrations used on crops--on the attachment of the bacteria to maize roots, since this step is of prime importance for the growth stimulation of the plant obtained with Azospirillum brasilense. In this paper we demonstrate that 2,4-D alters the bacterial adhesion to maize roots.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1996

Characterization of 2,4-dichlorophenoxyacetic acid transport and its relationship with polyamines in Azospirillum brasilense.

We have previously shown that 2,4-dichlorophenoxyacetic acid (2,4-D) inhibits Azospirillum brasilense growth, the synthesis of DNA, RNA and proteins. These toxic effects are prevented when polyamines are added to the culture medium. The purposes of our research were to determine the effects of the herbicide on the number of viable Azospirillum brasilense cells, characterize the 2,4-D transport system and to study the effects of polyamines upon the latter in this microorganism. We found that 2,4-D reduced the number of viable cells and that 2,4-D transport is energy-independent, since it was not affected by metabolic inhibitors. Polyamines did not alter 2,4-D uptake, further supporting the hypothesis that the herbicide most likely produces its toxic effects by interfering with the polyamine metabolism.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1996

Influence of body mass index and slimming habits on menstrual pain and cycle irregularity.

Using a cross-sectional sample of 1147 urban adolescents, aged between 14 and 20 years, the variability of some menstrual cycle indicators was related to weight loss. Nearly 40% of the adolescents tried to lose weight and the results showed that attempting to lose weight is significantly associated with increased prevalence of menstrual irregularity and menstrual pain. This finding is independent of body mass index.

Adolescent↗
PubMed1996

[Pilot experience with the use of an ambulatory geriatric assessment instrument].

BACKGROUND: Ten percent of the Chilean population is over 60 years old and general practitioners need an instrument to assess the degree of disability and multiple ailments of elders. AIM: To develop and use an instrument to assess elders consulting in primary care outpatient clinics. PATIENTS AND METHODS: An instrument to be used by general practitioners, aimed to assess bio-psico-social risk of elders was devised by the Geriatrics Program at the Faculty of Medicine of the Catholic University of Chile. The instrument was used in 100 elders (82 female) aged 71 +/- 8 years old consulting in a primary care outpatient clinic. RESULTS: The instrument took less than 5 minutes to be used. The most frequent risk factors found were living alone in 62% of subjects, falls in the last year in 47%, memory disturbances in 62%, overweight in 76%, visual impairment in 76%, urinary incontinence in 26% and depression in 76%. Thirty percent had difficulties to climb stairs and 4% had no support in case of severe disability. CONCLUSIONS: The applied instrument is fast to apply, easily understood by patients and detects problems associated with old age, that will help to plan primary care health programs.

Aged↗
PubMed1995

Effects of 2,4-dichlorophenoxyacetic acid on polyamine transport and metabolism in Azospirillum brasilense Cd.

We had previously demonstrated that 1 mM 2,4-D inhibited cell growth, nucleic acid synthesis and protein synthesis (at the ribosomal level) of Azospirillum brasilense. These alterations were prevented by the presence of polyamines in the culture medium. On the other hand, polyamines did not affect the 2,4-D uptake. In this paper we demonstrate that 2,4-D alters the metabolism of polyamines and increases their uptake.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1995

Parasitic infection in malnourished school children: effects on behaviour and EEG.

This paper describes a study of 194 children (aged 9-13) from a mountain village in Ecuador who were infected with one or more species of intestinal helminth or protozoan parasite. In addition to parasite load, the assessment consisted of a battery of psychological and neuropsychological tests, an EEG examination, measures of iodine level, presence of goitre and level of nutrition. We found that, in general, parasite infection, as measured at the baseline level, was not associated with cognitive impairment. The intensity of infection with A. lumbricoides, however, was correlated with the level of verbal ability and with inhibition-control aspects of cognitive behaviour. Multivariate analysis with level of nutrition, EEG status and parasite burden showed a consistent main effect of the degree of nutrition on neuropsychological performance, particularly the language, problem solving and inhibition-control dimensions.

Adolescent↗
PubMed1994

Serotype-specific detection of bean common mosaic potyvirus in bean leaf and seed tissue by enzymatic amplification.

An assay involving reverse transcription and polymerase chain reaction (PCR) is described for specific detection of serotypes A and B BCMV isolates in bean leaf and seed tissues. Three oligonucleotide primers designed according to the sequence data available allow, in appropriate combination, serotype-specific detection of BCMV. The sensitivity of the method was sufficient to detect BCMV in as little as 100 fg and 50 pg of infected leaf and seed tissues, respectively.

Base Sequence↗
PubMed1994

Evolutionary relationships among bean common mosaic virus strains and closely related potyviruses.

Bean common mosaic virus (BCMV) consists of a large number of strains with complex and controversial relationships among them and with other potyviruses that infect legumes. In order to elucidate the BCMV taxonomic pattern and its evolutionary implications, a phylogenetic analysis has been carried out. The analysis of the coat protein gene and 3' non-coding region (NCR) sequences recently obtained by us and other currently available potyviral sequences confirms the clustering of viruses comprised in BCMV strains with other closely related potyviruses and reveals the great informative content of 3' NCR, suggesting a more relevant role for this region in phylogenetic analysis.

Amino Acid Sequence↗
PubMed1993

The interaction of 2,4-dichlorophenoxyacetic acid, ribosomes and polyamines in Azospirillum brasilense.

2,4-Dichlorophenoxyacetic acid (2,4-D) is an herbicide used extensively in agriculture. We had previously determined that 1 mM 2,4-D could inhibit cell growth, DNA and protein synthesis of Azospirillum brasilense. The present work was designed to determine if these alterations are a consequence of 2,4-D action on polyamine biosynthesis and if the protein synthesis inhibition is a result of ribosomal impairment. In this paper we demonstrate that 2,4-D alters the metabolism of polyamines and, thus, affects protein synthesis at the ribosomal level.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1993

Performance of the copper T 200 in parous adolescents: are copper IUDs suitable for these women?

The clinical performance of a cohort of 995 parous adolescents, first-time users of the T-Cu 200B was studied and compared with a cohort of paired controls 10 years older, of the same parity. Life-table analysis showed that pregnancy, expulsion rates, as well as removals for bleeding and/or pain were higher in adolescents but within ranges already reported in the literature on this device. Removals for infection were few and not significantly different. Although the clinical performance of the T-Cu 200B in adolescents is not as good as in older women, the performance is similar or better than that reported for other reversible methods in this age group. Our conclusion is that IUDs should not be contraindicated for parous adolescents as long as adequate counseling, screening of risk factors, skillful insertion and follow-up are provided.

Adolescent↗
PubMed1992

Induction of C4-dicarboxylate transport genes by external stimuli in Rhizobium meliloti.

We have characterized two mutants of Rhizobium meliloti L5-30 obtained by random mutagenesis using Mu-lacZ that were defective in transport of C4-dicarboxylic acids. These mutants induced ineffective nodules on alfalfa. Mutations in the two strains appeared to be located in a dctA gene. Levels of dctA gene expression were determined under different environmental conditions using dctA-lacZ fusions, and beta-galactosidase activities increased in response to osmotic stress and also when the cells were incubated in medium low in calcium. The transcriptional induction of the dctA gene by environmental signals was decreased by DNA gyrase inhibitors such as novobiocin and coumermycin.

Aminocoumarins↗
PubMed1991

Serotonin immunoreactivity in the intermediate lobe of the rat pituitary.

Immunocytochemical staining for serotonin (5-HT) in paraffin-embedded sections of rat pituitary resulted in the localization of reactive nerve fibres and cell bodies in the intermediate lobe. Immunostaining was also found in the anterior and posterior lobes. Labelled nerve fibres appear to enter the intermediate lobe from the neural lobe through the interlobular spaces. These fibres are relatively scarce and lightly stained. Neuroglandular contacts were identified between varicose nerve endings containing serotonin and immunoreactive perykarion. It is not clear whether intermediate lobe cells produced 5-HT themselves or, alternatively, these cells take in 5-HT from serotoninergic nerve terminals.

Animals↗
PubMed1989

Subarachnoid haemorrhage of unknown aetiology.

The authors review the literature on subarachnoid haemorrhage of unknown aetiology (SAHUE) and analyze a personal series of 212 patients diagnosed as SAHUE. These patients represent 30% of all cases of primary SAH admitted over a 14.5 year period. The age, sex, antecedents and initial clinical presentation of patients with SAHUE were indistinguishable from those of patients with subarachnoid haemorrhage due to ruptured aneurysm (SAHRA). However, the present series of SAHUE compare favourably with both a personal and a previously reported series of SAHRA insofar as clinical grade on admission (94% of patients in grades I-II of Botterell), presence of blood on CT (51%), vasospasm (5%), ischaemic deficits (3.3%), persistent hydrocephalus (3.5%), rebleeding (6%) and fatal result (3.9%) are concerned. The amount of blood on CT scan in our patients with SAHUE was associated with a significantly higher incidence of brain ischaemia and hydrocephalus but did not correlate with the Botterell grade on admission or final outcome, which were good in the majority of cases regardless of the presence or not of visible cisternal haemorrhage. The results of the present series confirm that the final prognosis of patients with primary SAH showing normal four-vessel cerebral angiography is essentially favourable.

Adolescent↗
PubMed1989

Solubilization of the N-methyl-D-aspartate receptor channel complex from rat and porcine brain.

The N-methyl-D-aspartate (NMDA) receptor complex as defined by the binding of [3H]MK-801 has been solubilized from membranes prepared from both rat and porcine brain using the anionic detergent deoxycholate (DOC). Of the detergents tested DOC extracted the most receptors (21% for rat, 34% for pig), and the soluble complex, stabilized by the presence of MK-801, could be stored for up to 1 week at 4 degrees C with less than 25% loss in activity. Receptor preparations from both species exhibited [3H]MK-801 binding properties in solution very similar to those observed in membranes (Bmax = 485 +/- 67 fmol/mg of protein, KD = 11.5 +/- 2.9 nM in rat; Bmax = 728 +/- 108 fmol/mg of protein, KD = 7.1 +/- 1.6 nM in pig, n = 3). The pharmacological profile of the solubilized [3H]MK-801 binding site was virtually identical to that observed in membranes. The rank order of potency of: MK-801 greater than (-)-MK-801 = thienylcyclohexylpiperidine greater than dexoxadrol greater than SKF 10,047 greater than ketamine, for inhibition of [3H]MK-801 binding, was observed in all preparations. The receptor complex in solution exhibited many of the characteristic modulations observed in membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗