PubMed Health⌕ Search

Biomedical subjects

E Martinez

Publications and source records attributed to E Martinez.

At least 19 recordsLinked to original sources
PubMed1992

4-acetylaplykurodin B and aplykurodinone B, two ichthyotoxic degraded sterols from the Mediterranean mollusk Aplysia fasciata.

Two ichthyotoxic lactones, 4-acetylaplykurodin B [1] and aplykurodinone B [2], were isolated from the external parts of the body of the mollusk Aplysia fasciata. Their structures, determined by spectroscopic and chemical means, are closely related to aplykurodin B [3] previously isolated from Aplysia kurodai. The interconversion of delta- and gamma-lactones in the aplykurodin derivatives has been also investigated.

Animals↗
PubMed1992

Differing neurochemical and morphological sequelae of global ischemia: comparison of single- and multiple-insult paradigms.

The purpose of this investigation was to investigate pathomechanisms responsible for the deleterious effects of repeated episodes of brief forebrain ischemia. Halothane-anesthetized male Wistar rats were subjected to either (a) a single 15-min period or (b) three 5-min periods (separated by 1 h) of global forebrain ischemia by bilateral carotid artery occlusions plus hypotension (50 mm Hg), followed by various periods of recirculation. Brain temperature was normothermic throughout. In one series of rats, extracellular levels of glutamate, glycine, and gamma-aminobutyric acid (GABA) were measured in the dorsolateral striatum (n = 6-8 per group) and lateral thalamus (n = 4-6 per group) by microdialysis and HPLC before and during ischemia and during 3-5 h of recirculation. In a parallel series of rats (n = 6 per group), ischemic cell change was quantified at 2 (dark neurons), 24, or 72 h following either single or multiple ischemic insults. A single 15-min ischemic period led to massive glutamate release (13-fold increase; p = 0.001), which returned to normal by 20-30 min of recirculation and remained normal thereafter. By contrast, in rats with three 5-min periods of ischemia, the glutamate level rise with each repeated insult (four- to 4.5-fold; p < or = 0.02) was smaller than that observed during the single 15-min insult, but a late sustained rise (five- to six-fold; p < 0.05) occurred at 2-3 h of recirculation. Brief ischemia-induced elevations of glycine and GABA levels were detected in both the single- and multiple-insult groups, with normalization during recirculation. In contrast, the excitotoxic index, a composite measure of neurotransmitter release ([glutamate] x [glycine]/[GABA]), differed markedly following single versus multiple insults (p = 0.002 by repeated-measures analysis of variance) and increased by seven- to 12-fold (p < 0.05) at 1-3 h following the third insult. The total amount of glutamate released was 3.3-fold higher in the multiple-insult than in the single-insult group (p < 0.02). At 2 h of recirculation, histopathological analysis of dorsolateral striatum showed a significantly greater frequency of dark neurons in the multiple- than in the single-insult group (p < 0.05 by analysis of variance). In the thalamus, a higher frequency of ischemic neurons was seen in the multiple-than in the single-insult group at all intervals studied. Thus, in rats with multiple ischemic insults, accelerated ischemic damage was found in the striatum, and severe ischemic injury was documented in the thalamus.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of Variance↗
PubMed1992

Paraquat poisoning in children: survival of three cases.

Five children with paraquat poisoning are presented. Three were diagnosed early, treated and survived; the other 2 arrived 1-2 days after paraquat ingestion and died subsequently from respiratory failure due to pulmonary fibrosis.

Accidents↗
PubMed1991

Two- and three-color immunofluorescence using aminocoumarin, fluorescein, and phycoerythrin-labelled antibodies and single laser flow cytometry.

Antibodies coupled to 7-aminocoumarin (AMCA) emit a bright blue fluorescence under ultraviolet (UV) excitation and are therefore ideal for three-color immunofluorescence (IF) with fluorescein (FITC) and phycoerythrin (PE) labeled reagents; however, due to the different absorption spectra, the use of these fluorophores for multicolor flow-cytometric analysis requires a double light excitation source (e.g., two-laser system). We report a strategy which uses a single argon-ion laser to simultaneously excite AMCA, FITC, and PE, thus allowing the flow cytometric analysis of three immunological parameters. When the UV-visible argon-ion laser is fitted with an appropriate set of mirrors, the 35.1-363.8 nm (UV) and 488 nm wavelengths (accounting for 80 mW and 520 mW, respectively) are simultaneously generated; these lines can then be exactly focused on the same observation point by an achromatic cylindrical lens. A number of comparative analysis were performed with this instrumental set up to verify the sensitivity of AMCA IF and its possible application for multicolor immunophenotypic evaluation of blood cell subsets. When AMCA- and FITC-labeled antimouse Ig antibodies were assessed for their ability to detect limiting amounts of mouse monoclonal antibody bound to cells, the former was less sensitive than the latter. A number of factors, including differences in excitation energy (80 mW for AMCA and 520 mw for FITC) and extinction coefficients (1.9 x 10(4) for AMCA and 6 x 10(4) for FITC) could explain this result.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Anti-Idiotypic↗
PubMed1991

A common ancestor DNA motif for invertebrate and vertebrate hormone response elements.

The ecdysone-responsive DNA sequence of the Drosophila hsp27 gene promoter contains four direct and inverted repeats reminiscent of those that compose the vertebrate palindromic estrogen response element (ERE) and the thyroid hormone/retinoic acid response element (TRE/RRE). Interestingly, a 3 bp substitution in the wild-type Hsp27 ecdysone response element (EcdRE) increases both its similarity with the vertebrate ERE and TRE/RRE and its capacity to confer ecdysone responsiveness to a heterologous promoter. Remarkably, increasing the spacing between the inverted repeats of this strong EcdRE by two nucleotides converts it into an ERE. Inversely, decreasing the spacing between the two inverted repeats of the vertebrate consensus palindromic ERE, from three to one nucleotide, converts it into a functional EcdRE. Thus, the only difference between an invertebrate EcdRE and a vertebrate palindromic ERE or TRE/RRE is in the spacing between the conserved inverted repeated motifs forming these palindromic HREs. The finding that the sequence motif 5'-GGTCA-3' present in the vertebrate ERE and TRE/RRE is also a functionally important characteristic of an invertebrate HRE, suggests that a common ancestor regulatory DNA sequence gave rise to all HREs known so far. We discuss the possibility that this progenitor motif is the GGTCA sequence.

Animals↗
PubMed1991

Ultrastructural cryoimmunocytochemistry is a convenient tool for the study of DNA replication in cultured cells.

In the present study, we have optimized an immunocytochemical ultrastructural approach for in situ localization of newly synthesized DNA in unsynchronized as well as in synchronized human HeLa cells and in exponentially growing mouse P815 cells, which had incorporated bromodeoxyuridine (BrdU) during short pulses varying from 1 to 20 minutes. The incorporated BrdU was detected in hydrolyzed ultrathin cryosections or Lowicryl sections by means of a monoclonal antibody, revealed by secondary colloidal gold-labeled probes. The results demonstrate our ability to study, with high resolution and reproducibility, DNA replication during consecutive periods of the S-phase, which is monitored by the incorporation of tritiated thymidine. In addition, this approach allows one to perform a concomitant mapping of replicated DNA and various enzymes of the replisome.

Animals↗
PubMed1991

Organisation and functions of the actVA region of the actinorhodin biosynthetic gene cluster of Streptomyces coelicolor.

Sequence analysis of the actVA region of the actinorhodin biosynthetic gene cluster of Streptomyces coelicolor revealed a succession of six open reading frames (ORFs), all running in the same direction and extending over 5.32 kb. The protein product of actVA-ORF1 strongly resembles that of another gene, elsewhere in the act cluster (actII-ORF2), which codes for a trans-membrane protein previously implicated in actinorhodin export from the mycelium. This suggests that the two gene products may co-operate in actinorhodin export, perhaps being sufficient for self-protection of the organism against suicide. At least four of the other five ORFs are implicated in the control of the C-6 and C-8 ring-hydroxylation reactions, lacking in actVA mutants, that occur at middle to late stages in the actinorhodin biosynthetic pathway. This conclusion was reached by genetic mapping of actVA mutants to actVA-ORF3 and -ORF5 (and perhaps -ORF4), and by the finding of strong resemblances between the protein products of actVA-ORF2 and -ORF6 and the products of genes of the oxytetracycline or tetracenomycin gene clusters that have been implicated in ring-hydroxylation reactions in the biosynthesis of these other aromatic polyketide antibiotics.

Amino Acid Sequence↗
PubMed1991

Superfamily of steroid nuclear receptors: positive and negative regulators of gene expression.

The nuclear hormone receptor superfamily is characterized by an impressive functional diversity of its members despite a remarkable overall structural unity. A variety of ligands bind specifically to them and these receptors control gene networks that have profound effects on growth, development, and homeostasis. The ligand-receptor complexes recognize transcriptional enhancer DNA sequences, the hormone response elements, resulting in induction or repression of gene activity. The similarity between all these hormone response enhancer elements, as well as between the receptors themselves, indicates a conserved general strategy for the hormonal control of transcription by steroids. The activated receptors bind to responsive promoters and most likely mediate the assembly of stage- and tissue-specific transcription factor complexes that stimulate or inhibit gene expression.

Animals↗
PubMed1991

Acute oculogyric crisis after administration of prochlorperazine.

We report a case of acute oculogyric crisis due to prochlorperazine administration in a young black woman with a concomitant viral infection. Neuroleptic medications are the most common cause of drug-induced acute dystonic reactions such as oculogyric crisis. Prochlorperazine is an antiemetic agent with a phenothiazine-type chemical structure and is known to cause dystonic reactions. Drug-induced acute dystonic reactions are most common in young adults and in men. Viral infections may also predispose patients to these adverse reactions. Caution is warranted when this drug is used in patients who have other risk factors for an acute dystonic reaction.

Acute Disease↗