Immunohistochemical study of experimental acute cellular rejection.
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Acute Disease↗
Biomedical subjects
A Ramos
Publications and source records attributed to A Ramos.
Some non-linear aspects of the electronic stages in time-domain modelling of NDE pulse-echo ultrasonic systems.
Electronics interfacing with NDE probes frequently include non-linear switching devices and semiconductor networks, which influence the excitation pulses and detected echo signals. Classical approaches to modelling a pulse-echo process use ideal assumptions for the electronics and do not consider these influences on the echoes, which can be very relevant in HF cases. This paper proposes new ways to consider these non-linear effects in a time-domain simulation process, extending previous approaches by including new elements in the modelling. Specific electrical models covering the pulse-echo process are applied in the evaluation of echo-graphic signals. They include semiconductor devices and other non-ideal elements. From these models, and using SPICE as a simulation tool, strong non-linear effects on pulsed responses, computed for both E/R stages of typical NDE transceivers, are analysed.
Journal Article↗
Influence of thresholding procedures in ultrasonic grain noise reduction using wavelets.
Wavelet transform based techniques are used for signal-to-noise ratio (SNR) enhancement in ultrasonic non-destructive testing and evaluation of strong sound scattering materials. The overall denoising performance of a wavelet signal processor is conditioned by several processing parameters, including the type of wavelet, thresholding method, and threshold selection rules. Different thresholding procedures and threshold selection rules are analysed in this paper using the discrete wavelet transform and decomposition level dependent thresholds. Global performance is evaluated by means of the SNR enhancement using synthetic grain noise registers with an incrusted flaw signal, with different values of the input SNR, and experimental ultrasonic traces acquired from a carbon fibre reinforced plastic composite block.
Journal Article↗
The effect of dissolved glyphosate upon the sorption of copper by three selected soils.
The effect of the pesticide glyphosate (GPS) on adsorption processes of copper onto three soils of different characteristics has been studied. Cu adsorption decreases in general with increasing GPS concentration in solution, due principally to the lower equilibrium pHs, although this is not the only variable affecting copper adsorption. For the same pH values, Cu adsorption is higher in two of the three soils in the presence of GPS, but for the third soil, Cu adsorption is higher in the absence of GPS. This behavior is explained by the possibility of GPS adsorption on these soils and by the formation of Cu-GPS complexes in solution. The soils showing a higher Cu adsorption in the presence of GPS than in its absence for the same pH are able to adsorb this pesticide. In these soils, copper can be adsorbed directly on the soil surfaces, and also through the formation of bonds with GPS previously adsorbed. The third soil was not able to adsorb GPS. Consequently, all the pesticide remained in solution, forming strong Cu complexes with low tendency to be adsorbed on this soil. For this reason, the concentration of free Cu in solution is drastically reduced, and the adsorption of copper on this soil is lower.
Adsorption↗
Molecular genetic approaches to investigate individual variations in behavioral and neuroendocrine stress responses.
A large response range can be observed in both behavioral and neuroendocrine responses to environmental challenges. This variation can arise from central mechanisms such as those involved in the shaping of general response tendencies (temperaments) or involves only one or the other output system (behavioral vs. endocrine response). The participation of genetic factors in this variability is demonstrated by family and twin studies in humans, the comparison of inbred strains and selection experiments in animals. Those inbred strains diverging for specific traits of stress reactivity are invaluable tools for the study of the molecular bases of this genetic variability. Until recently, it was only possible to study biological differences between contrasting strains, such as neurotransmitter pathways in the brain or hormone receptor properties, in order to suggest structural differences in candidate genes. The increase of the power of molecular biology tools allows the systematic screening of significant genes for the search of molecular variants. More recently, it was possible to search for genes without any preliminary functional hypothesis (mRNA differential expression, nucleic acid arrays, QTL search). The approach known as quantitative trait loci (QTL) analysis is based on the association between polymorphic anonymous markers and the phenotypical value of the trait under study in a segregating population (such as F2 or backcross). It allows the location of chromosomal regions involved in trait variability and ultimately the identification of the mutated gene(s). Therefore, in a first step, those studies skip the 'black box' of intermediate mechanisms, but the knowledge of the gene(s) responsible for trait variability will point out to the pathway responsible for the phenotypical differences. Since variations in stress-related responses may be related to numerous pathological conditions such as behavioral and mood disorders, drug abuse, cardiovascular diseases or obesity, and production traits in farm animals, these studies can be expected to bring significant knowledge for new therapeutic approaches in humans and improved efficiency of selection in farm animals.
Animals↗
[Arteriovenous malformation of the middle and posterior third section of the corpus callosum treated with embolization and surgery].
We are presenting the case of a 58 year-old woman with an arteriovenous malformation (AVM) of the middle and posterior thirds of the corpus callosum which had produced two episodes of bleeding before admission to our Department, when the patient was neurologically intact. The nidus was fed by the anterior and posterior pericallosal arteries draining through the left medial atrial vein to the vein of Galen, by parasagittal cortical veins to the superior sagittal sinus and by right temporal veins to the sphenoparietal sinus. The patient underwent embolization of the anterior and posterior feeders in two sessions separated by a week interval, and then the AVM was removed through a left paramedial parietooccipital craniotomy in a single stage. The patient showed transient mild short term memory deficit, but the final outcome was excellent.
Agenesis of Corpus Callosum↗
[The fate of podocytes in proteinuric nephropathies].
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Animals↗
Protein phosphatase methyltransferase 1 (Ppm1p) is the sole activity responsible for modification of the major forms of protein phosphatase 2A in yeast.
Protein phosphatase 2A (PP2A) is a major threonine/serine phosphatase that is involved in regulating a variety of cellular processes. It has been shown in both yeast and mammals that the PP2A catalytic subunit (PP2Ac) is methyl-esterified at the conserved C-terminal Leu residue. The recent characterization of a mammalian PP2A carboxyl methyltransferase has led to the identification of two ORFs in Saccharomyces cerevisiae as potential orthologues of the mammalian PP2A methyltransferase: protein phosphatase methyltransferase 1 (PPM1) and protein phosphatase methyltransferase 2 (PPM2). To experimentally identify the PP2A methyltransferase in yeast, we obtained deletion mutants of PPM1 and PPM2 and then constructed double mutants. Using in vivo-labeling techniques, we demonstrate that only the PPM1 gene is required for PP2Ac methylation at the C-terminus. Because yeast has at least three homologues of PP2Ac (PPH21, PPH22, and PPH3), we then asked whether all of these catalytic subunits are methylated by the PPM1 and/or PPM2 putative methyltransferases. We modified the segment corresponding to the N-terminal coding region of all three PP2Ac genomic genes with a hemagglutinin (HA) tag in the parent, ppm1, ppm2, and ppm1ppm2 mutant genetic backgrounds. Using immuoprecipitation with anti-HA antibodies followed by methyl ester analysis, we showed that only in the ppm1 mutant were both Pph21p and Pph22p not methylated. We did not detect any methylesterification of Pph3p under our conditions. Our results indicate that PPM1 is the sole methyltransferase responsible for methylating the two major homologues of PP2Ac in yeast. The function of the PPM2 gene product remains unclear.
DNA Methylation↗
Traumatic cervical central cord syndrome due to intramedullary hemorrhage studied with MRI: case presentation.
Cervical central cord syndrome is characterized by disproportionately greater motor impairment of the upper than the lower extremities, predominantly distal motor dysfunction, varying degrees of sensory abnormalities, and bladder dysfunction. Although the original description stated that intramedullary hemorrhage is a possible cause of traumatic cervical central cord syndrome, recent studies have not demonstrated its presence on the basis of magnetic resonance imaging (MRI) or pathological evidence. The authors describe and discuss a case of traumatic central cervical cord syndrome studied with MRI, which presented intramedullary hemorrhage. This supports hemorrhage as a possible cause of traumatic cervical central cord syndrome.
Aged↗
Receptor binding properties of di (1,N6-ethenoadenosine) 5', 5'''-P1, P4-tetraphosphate and its modulatory effect on extracellular glutamate levels in rat striatum.
Our aim was to investigate the neuromodulatory role of diadenosine tetraphosphate (Ap(4)A). Ap(4)A-binding sites were detected in striatum and hippocampus membranes using [(35)S]-ADP beta S as radioligand and Ap(4)A and epsilon-(Ap(4)A), di-ethenoadenosine tetraphosphate, as displacers. Effects of epsilon-(Ap(4)A) on extracellular glutamate levels were studied using intracerebral perfusion. Both areas contain high-affinity binding sites for [(35)S]-ADP beta S with K(d) values in the low nM range. [(35)S]-ADP beta S binding was displaced by Ap(4)A and epsilon-(Ap(4)A). At 1 and 10 microM doses, epsilon-(Ap(4)A) markedly decreased glutamate levels in the striatum. The possibility of Ap(4)A acting as an endogenous modulator of excitatory neurotransmission is discussed.
Adenosine Diphosphate↗
Fluid collections and juxta-articular cystic lesions of the shoulder: spectrum of MRI findings.
The MR imaging features of fluid collections and juxta-articular cystic lesions of the shoulder are discussed, with special focus on those related to subacromial impingement and rotator cuff tears. Other more unusual fluid collections and cystic lesions are described, including rice-bodies bursitis, idiopathic synovial osteochondromatosis, dialysis-related amyloid arthropathy, hemophilic arthropathy, infectious conditions, non-infectious inflammatory arthritis, and paralabral cysts.
Humans↗
Mutagenicity and antioxidant assessment of Stachitarpheta jamaicensis (L.) Vahl.
Stachitarpheta jamaicensis (L.) Vahl. is a member of the Verbenaceae commonly used in Cuba, mainly as vermifugue and against diarrhoea. The mutagenic potential of a hydroalcohol extract of its aerial parts was assessed in vitro using the Salmonella/microsome assay and in vivo in the mouse bone marrow micronucleus test. No positive response was observed in a battery of four Salmonella typhimurium strains employed: TA 1535, TA 1537, TA 98 and TA 100, when exposed to concentrations up to 5 mg/plate, with and without mammalian metabolic activation. In the same way, no increase in the micronucleus frequency in mitotic erythropoietic tissue was observed when animals were administered the extract orally in doses of 500, 1000 and 2000 mg/kg. The extract inhibited lipid peroxidation in the rat liver microsomal fraction (IC(50) = 3.6 microg/mL) but it does not seem to be an effective.OH radical scavenger (IC(50) = 76.7 microg/mL). Noteworthy, it increased in a dose dependent way the level of revertant colonies in E. coli IC 203, a strain sensitive to oxidative mutagenesis, when assayed together with hydrogen peroxide and ferrous sulphate, which suggests a pro-oxidant action.
Animals↗
Agenesis of the internal carotid artery with a trans-sellar anastomosis: CT and MRI findings in late-onset congenital hypopituitarism.
A 29-year-old woman with a history of hypothyroidism since early childhood developed hypopituitarism. CT and MRI revealed anterior pituitary hypoplasia, an ectopic posterior lobe, a Chiari I malformation and agenesis of the right internal carotid artery with a trans-sellar anastomosis. This constellation of findings constitutes a previously unreported association in congenital hypopituitarism of late onset. The usefulness of imaging modalities and the pathogenic implications are also discussed.
Abnormalities, Multiple↗
Dorsal defect on a multi-partite patella: imaging findings.
Coincidence of dorsal defect on a multipartite patella constitutes a rare cause of anterior knee pain in the first decades of life. Imaging findings of this uncommon symptomatic skeletal variant are discussed, with emphasis on MR features.
Adolescent↗
The cell division genes ftsQ and ftsZ, but not the three downstream open reading frames YFIH, ORF5 and ORF6, are essential for growth and viability in Brevibacterium lactofermentum ATCC 13869.
The three ORFs (YFIH, ORF5 and ORF6) located downstream of the cell division genes ftsQ and ftsZ in Brevibacterium lactofermentum were disrupted by single homologous recombination events between internal fragments of the corresponding genes and the chromosomal sequences. The phenotypes of the disrupted mutants were similar to that of the wild type, suggesting that these genes are dispensable for growth and viability. However, using different plasmid constructs, it was not possible to obtain disrupted ftsZ or ftsQ mutants by single crossover events. When the ftsZ or ftsQ gene sequence was disrupted in vitro and used to replace the homologous chromosomal gene by double recombination, only single recombination events took place, and therefore no disruptants were obtained. It may be concluded therefore that, as in Escherichia coli, the cell division genes ftsQ and ftsZ are indispensable for growth and viability of B. lactofermentum. Northern hybridisation analyses performed using internal fragments of the genes coding for YFIH, ORF5 and ORF6 allowed us to dissect their transcriptional organization and to confirm the disruption of these genes.
Bacterial Adhesion↗
Intracranial hemangiopericytoma: study of 12 cases.
Most hemangiopericytomas (HPCs) are located in the musculoskeletal system and the skin, while the intracranial location is rare. They represent 2 to 4% in large series of meningeal tumours, thus accounting for less than 1% of all intracranial tumours. Many authors have argued about the true origin of this tumour. The current World Health Organization classification of Central Nervous System tumours distinguishes HPC as an entity of its own, and classified it into the group of "mesenchymal, non-meningothelial tumours". Radical surgery is the treatment of choice, but must be completed with postoperative radiotherapy, which has proved to be the therapy most strongly related to the final prognosis. HPCs have a relentless tendency for local recurrence and metastases outside the central nervous system which can appear even many years after diagnosis and adequate treatment of the primary tumour. Twelve patients with intracranial HPC were treated at our Unit between 1978 and 1999. There were 10 women and 2 men. Ten tumours were supratentorial and most located at frontoparietal parasagittal level. The most common manner of presentation was a focal motor deficit. All tumours were hyperdense in the basal Computed Tomography scans and most enhanced homogeneously following intravenous contrast injection. In 50% of cases, tumour margins were irregular or lobulated. Seven tumours were studied with Magnetic Resonance Imaging, being six of them iso-intense with the cortical gray matter on T1-weighted and T2-weighted images. Twenty operations were performed in the 12 patients. In 10 cases radical excision could be achieved with no operative mortality. Total recurrence rate was 33.3%. Eight patients were treated with external radiotherapy at some time through the course of their disease. Eight out of the 12 patients in this series are disease-free (Glasgow Outcome Scale categories 1 and 2) after a mean follow up of 52 months.
Adolescent↗
Ganglioglioma of the brainstem: report of three cases and review of the literature.
BACKGROUND: Brainstem gangliogliomas are rare low-grade tumors that usually have a long clinical history. However, they may cause sudden death. There are only 31 cases of brainstem ganglioglioma reported in the literature, and only one has been studied with magnetic resonance (MR). We present three new cases of brainstem ganglion cell tumor studied with computed tomography (CT) (3 cases) and MR (2 cases) and discuss the clinical presentation, diagnostic imaging and treatment of these tumors. CASE DESCRIPTION: Age at presentation ranged from 19 to 59 years old. Two patients were female and 1 male. Duration of symptoms before diagnosis ranged from 1 year to nearly 14 years. Presenting complaints included syncope spells, cranial nerve deficits, headache, and gait instability. Imaging studies revealed well-circumscribed lesions involving the brainstem; the lesion was cystic in one case and calcified in one. They were iso- or hyperdense on CT scan, isodense on T1-weighted and hyperdense on T2-weighted MRI and frequently showed contrast enhancement. All tumors were operated through a posterior fossa craniectomy. Using microsurgical techniques only partial resection could be achieved, as there was no sharp delineation from the surrounding tissue in any case. Two of our patients had increased neurological deficits after surgery. Radiotherapy was not given. Follow-up of tumoral remnants has not shown clear tumor growth after 1, 3.5, and 10 years. CONCLUSIONS: Imaging characteristics of brainstem gangliogliomas do not seem to differ from those in other locations and are not specific. Radical surgery is rarely if ever possible, nor is it advisable because of the risk of functional deterioration. However, because of their benign histology, partial resection seems to carry a similar prognosis as tumors in other locations that are amenable to complete resection.
Adult↗
Assessment of mutagenicity in Parthenium hysterophorus L.
The mutagenic potential of a crude extract of Parthenium hysterophorus L. was assessed in the Salmonella/microsome (Ames) assay and the mouse bone marrow micronucleus test. Results in the bacterial mutagenicity assay were negative for the five strains employed, e.g. TA 1535, TA1537, TA 98, TA 100 and TA 102, while cytotoxicity was evident in all cases at 5000 microg per plate, the highest concentration assayed. A decrease in toxicity was observed with exogenous mammalian metabolic activation (S9) or glutathione (5 micromol per plate). When mutagenicity was monitored after column chromatography fractionation of the crude, fraction 1 was mutagenic in strain TA 98 (+S9). Besides, cytotoxicity was found in fraction 5, where parthenin was eluted. The micronucleus test was negative in mice upon oral administration, at doses up to 96 mg of crude per kg. Bone marrow toxicity was not observed. The crude extract exhibited some in vitro pro-oxidant activity. It also inhibited lipid peroxidation (IC(50)=4.1 microg/ml) but failed to act as .OH scavenger.
Animals↗