Whole-body magnetic resonance imaging in children: state of the art / Ressonância magnética de corpo inteiro em pediatria: estado da arte

Whole-body imaging in children was classically performed with radiography, positron-emission tomography, either combined or not with computed tomography, the latter with the disadvantage of exposure to ionizing radiation. Whole-body magnetic resonance imaging (MRI), in association with the recently developed metabolic and functional techniques such as diffusion-weighted imaging, has brought the advantage of a comprehensive evaluation of pediatric patients without the risks inherent to ionizing radiation usually present in other conventional imaging methods. It is a rapid and sensitive method, particularly in pediatrics, for detecting and monitoring multifocal lesions in the body as a whole. In pediatrics, it is utilized for both oncologic and non-oncologic indications such as screening and diagnosis of tumors in patients with genetic syndromes, evaluation of disease extent and staging, evaluation of therapeutic response and post-therapy follow-up, evaluation of non neoplastic diseases such as multifocal osteomyelitis, vascular malformations and syndromes affecting multiple regions of the body. The present review was aimed at describing the major indications of whole-body MRI in pediatrics added of technical considerations.

A avaliação de corpo inteiro em crianças era classicamente realizada com radiografias simples, cintilografia e tomografia por emissão de pósitrons combinada ou não à tomografia computadorizada, estes com a desvantagem de exposição à radiação ionizante. A ressonância magnética de corpo inteiro (RMCI), associada ao desenvolvimento de técnicas metabólicas e funcionais como difusão, trouxe a vantagem de uma avaliação global do paciente pediátrico sem os riscos da radiação ionizante habitualmente presente nos métodos radiológicos convencionais. A RMCI é um método rápido e sensível, com aplicação especial na área de pediatria na detecção e no monitoramento de lesões multifocais no corpo como um todo. Em pediatria, esta técnica é utilizada tanto em oncologia - no diagnóstico e rastreamento de tumores em pacientes portadores de síndromes genéticas, na avaliação da extensão de doenças e estadiamento oncológico, na avaliação da resposta terapêutica e no seguimento pós-terapêutico - como em lesões não neoplásicas - osteomielite multifocal, malformações vasculares e síndromes que comprometam múltiplas regiões do corpo. Esta revisão tem como objetivo mostrar as principais indicações do exame na população pediátrica e técnica de realização.

Expression of p35 and p25 after Focal Cerebral Contusion in Rat / 法医学杂志

OBJECTIVE@#To study the expression of p35 and p25 in rat after focal cerebral contusion and to provide experimental data for estimating brain injury time.@*METHODS@#Fifty adult male SD rats were randomly divided into 0 h, 6 h, 12 h, 24 h, 3 d, 5 d, 7 d, 10 d after focal cerebral contusion, control and sham-operated groups (5 rats each group). The focal cerebral contusion rat model was established. The expression of p35 and p25 protein of the damage peripheral zone in brain were detected by HE staining, immunohistochemistry and Western blotting at different injury time.@*RESULTS@#A large number of p35 protein and a small amount of p25 protein were expressed in control group and sham-operated group. After focal cerebral contusion, p35 presented unimodal change with time and p25 presented bimodal changes with time.@*CONCLUSION@#Expression of p35 and p25 showed different regularity with good time correlation, which could help to estimate the brain injury time.

Lung Retinoid Metabolism and Signaling in Chronic Obstructive Pulmonary Disease.

There are a number of sites that are required for the production and/or action of all-trans retinoic acid (ATRA). In particular, interruption of different components of the chain of trafficking and metabolism has been associated with cancers arising in numerous organs of the body. Preliminary work suggests that such interruptions may be a factor in lung disorders induced by the smoke exposure. The active metabolite of retinoid, ATRA offers a therapeutic strategy to protect against functional abnormality in the lung, including chronic obstructive pulmonary disease (COPD). This review deals with the lung retinoid metabolism and mediators of retinoid trafficking and signaling with special emphasis on their roles in health and disease.

Neuronal loss in primary long-term cortical culture involves neurodegeneration-like cell death via calpain and p35 processing, but not developmental apoptosis or aging

Primary neuronal culture is a powerful tool to study neuronal development, aging, and degeneration. However, cultured neurons show signs of cell death after 2 or 3 weeks. Although the mechanism underlying this phenomenon has not been elucidated, several preventive methods have been identified. Here we show that the neuronal loss in primary cortical culture involves calpain activation and subsequent neuronal cell death. Neuronal loss during cultivation showed destruction of neurites and synapses, and a decrease in neuron numbers. micro-Calpain and micro-calpain were initially activated and accumulated by increased RNA expression. This neuronal death exhibited neurodegenerative features, such as conversion of p35 to p25, which is important in the developmental process and in the pathogenesis of Alzheimer's disease. But, postnatal and aged rat cortex did not show calpain activation and prolonged processing of p35 to p25, in contrast to the long-term culture of cortical neurons. In addition, the inhibition of calpains by ALLM or ALLN blocked the conversion of p35 to p25, indicating that the calpain activity is essential for the neurodegenerative features of cell death. Taken together, this study shows that the neuronal loss in primary cortical cultures involves neurodegeneration-like cell death through the activation of calpains and the subsequent processing of p35 to p25, but not developmental apoptosis or aging. Our results suggest that the long term primary culture of cortical neurons represent a valuable model of neurodegeneration, such as Alzheimer's disease.

Fosforilación de tau y enfermedad de Alzheimer / Phosphorylation of Tau and Alzheimer's Disease

Tau forma parte importante del citoesqueleto en neuronas; estabilizando microtúbulos, manteniendo la forma celular y como via de transporte axonal. Sin embargo, por mecanismos desconocidos, tau sufre modificaciones importantes como son fosforilación anormal debida a la actividad desequilibrada de varias cinasas y fosfatasas, afectando su función biológica normal. Bajo estas circunstancias tau comienza a agregarse originando complejos proteicos denominados desarreglos neurofibrilares (NFTS) que son hallazgos histopatológicos característicos de la enfermedad de Alzheimer junto con las placas seniles. Esta revisión esta enfocada principalmente a describir la estructura de tau y la participación de diferentes cinasas en su regulación.

Tau is an important component of neuronal cytosqueleton; the protein stabilizas microtubules, maintains cell shape and axonal transport mechanisms. Howevwe, for unknown reasons tau experiments important postranslation modifications including enhanced phosphorylation due to unbalanced activity between kinases and phosphatases, affecting its normal biological function. Under these circumstances tau begins to aggregate into neurofibrillary tangles (NFTS) complexes which are pathological hallmarks of Alzheimer's disease together with senile plaques. This review is mainly concerned with the role that different kinase play into the regulation of tau structure and function.

Phosphorylation of ryanodine receptors

Both cardiac and skeletal muscle ryanodine receptors (RyRs) are parts of large complexes that include a number of kinases and phosphatases. These RyRs have several potential phosphorylation sites in their cytoplasmic domains, but the functional consequences of phosphorylation and the identity of the enzymes responsible have been subjects of considerable controversy. Hyperphosphorylation of Ser-2809 in RyR2 (cardiac isoform) and Ser-2843 in RyR1 (skeletal isoform) has been suggested to cause the dissociation of the FK506-binding protein (FKBP) from RyRs, producing "leaky channels," but some laboratories find no relationship between phosphorylation and FKBP binding. Also debated is the identity of the kinases that phosphorylate these serines: cAMP-dependent protein kinase (PKA) versus calmodulin kinase II (CaMKII). Phosphorylation of other targets of these kinases could also alter calcium homeostasis. For example, PKA also phosphorylates phospholamban (PLB), altering the Sarco-endoplasmic reticulum Ca2+ ATPase (SERCA) activity. This review summarizes the major findings and controversies associated with phosphorylation of RyRs.

Putative pyrophosphate phosphofructose 1-kinase genes identified in sugar cane may be getting energy from pyrophosphate

Pyrophosphate-dependent phosphofructokinase (PPi-PFK) has been detected in several types of plant cells, but the gene has not been reported in sugar cane. Using Citrus paradisi PPi-PFK gene (AF095520 and AF095521) sequences to search the sugar cane EST database, we have identified both the alpha and beta subunits of this enzyme. The deduced amino acid sequences showed 76 and 80 similarity with the corresponding alpha and beta subunits of C. paradisi. A high degree of similarity was also observed among the PFK b subunits when the alignment of the sugar cane sequences was compared to those of Ricinus communis and Solanum tuberosum. It appears that alpha and beta are two distinct subunits; they were found at different concentrations in several sugar cane tissues. It remains to be determined if the different gene expression levels have some physiological importance and how they affect sucrose synthesis, export, and storage in vacuoles. A comparison between the amino acid sequences of b PFKs from a variety of organisms allowed us to identify the two critical Asp residues typical of this enzyme's activity site and the other binding sites; these residues are tightly conserved in all members of this protein family. Apparently, there are catalytic residues on the b subunit of the pyrophosphate-dependent enzyme

An overview of pathophysiology and treatment of insulin resistance.

Insulin resistance has emerged out as a concept linking diabetes mellitus and hypertension. Clinically it is characterized by hyperinsulinemia, hypertension, central obesity, abnormal lipid profile and cardiovascular complications. Insulin resistance is often associated with presence of anti-insulin antibodies and absent or dysfunctional insulin receptors. At molecular level insulin resistance appears to occur at the level of G-protein, kinase activation, glucose carriers (GLUT) and gene expression. Although with advent or research, the molecular mechanisms of insulin resistance are becoming more clear and there is development of new therapeutic agents like insulin sensitizers (thizolidinediones), in clinical practice, as of today, a patient with insulin resistance is looked upon as hypertensive or having diabetes mellitus. Accordingly he is taking either antihypertensives or antidiabetic drugs or both. It is thus essential to look into effects of these agents on insulin sensitivity. In recent years some scattered studies have been conducted to evaluate the effect of various antihypertensives and antidiabetics on insulin sensitivity. An antihypertensive or antidiabetic drug should directly benefit the cardiovascular risk profile of these patients. Although various newer approaches are explored to have a therapeutic benefit in insulin resistance, it is still a long way in the research, when a suitable pharmacological agent with least untoward effects will be available for the treatment of insulin residence.

Early molecular signals induced by antibodies to GPI-anchored proteins

We have examined intracellular biochemical and metabolic changes induced by antibodies specific for glycosylphosphatidylinositol (GPI)-anchored cell surface molecules. In lymphoid cells the earliest detectable responses are phosphorylation of intracellular substrates. The GPI-linked target antigens are also rapidly redistributed into patches and caps on the cell surface and then internalised. Between two and five hours later, cytokine receptors are expressed. Later, cells become metabolically active and begin to proliferate and express endogenous cytokines, thus promoting autocrine growth. Very early events, such as kinase activity, are induced by antibody binding alone and are characteristic of the cell surface molecule recognised by antibodies. Thus, the initial events in the activation cascade are critical in selecting the metabolic route. Progression down the activation cascade requires further signals such as cross-linking antibodies, exogenous cytokines, phorbol esters, or accessory cells. Once in cycle, cells no longer display evidence of their original route of activation. Activated T lymphocytes acquire resitance to cleavage by GPI-specific phospholipase C, suggesting a possible feedback mechanism to limit cell proliferation

Beta-adrenergic modulation of rat brain insulin receptor activity in normal and hyperglycaemic conditions.

The [125I]Insulin binding and receptor kinase activity were assessed in rat brain in the presence of 10 microM concentrations of the beta agonist isoproterenol. While insulin binding remained unaltered, beta agonist treatment enhanced significantly receptor kinase activity in control and hyperglycaemic conditions. Antihyperglycaemic effects of isoproterenol were discussed in relation to adrenergic effects on insulin action in brain.

Phosphorylation of proteins in virulent promastigotes from Leishmania major

Protein kinases are present in the plasma membrane of the human parasite Leishmania. A marked increase in enzyme activity has been detected as cultures entered into the stationary phase of growth. Since avirulent parasites can be separated from virulent forms by the peanut agglutinin (PNA), we have examined the change in the protein kinase activity of L. major during growth in vitro and the difference in phosphorylation with virulent promastigotes (PNA-) of L. major. Marked similarities were found between the phosphorylation patterns of the logarithmic and stationary phase promastigotes of L. major. On the other hand, when the phosphorylation pattern of those proteins, shared by both the metacyclic (PNA-) promastigotes and the stationary phase cells, was examined, a marked increase in both the total number of phosphoproteins and the extent of their phosphorylation was observed in PNA-. Both the increase in protein kinase activity in the stationary phase parasites and the marked changes in phosphorylation in the highly infective promastigotes, may provide a clue as to the adaptative mechanism which enable promastigotes to survive within the vertebrate host

Sucrose metabolism in developing endosperm of immature wheat (Triticum aestivum L.) grain.

With a view to investigating the role of the enzyme pyrophosphate-fructose-6-phosphate-1-phosphotransferase (PFP) in sucrose breakdown in developing endosperm of wheat grain, the activity of PFP and related enzymes such as phosphofructokinase (PFK), fructose-6-bisphosphatase (FBPase), fructose-6-phosphate-2-kinase (PFK-2) and fructose-2,6-bisphosphatase (F2, 6-P2ase) and the contents of the various intermediates of the pathway serving either the substrate or the effectors of these enzymes such as glu-6-P,glu-1-P,fru-6-P,fru-1,6-P2,DHAP,G3P, UDP-glucose, ADP-glucose, Pi,PPi and fru-2,6-P2 have been determined at 5 days intervals starting from day-5 after anthesis until day-40 after anthesis. These enzymes except PFK-2 had their peak activity at day-25 after anthesis. The activity of PFP was several fold higher than that of PFK at each stage of grain development. PFK-2 exhibited the lowest activity. The various intermediates again had their maximum concentration either at day-20 or day-25 after anthesis. Among hexose phosphates studied, glu-6-P was present in highest concentration at each stage of grain development. The level of Pi was much higher than those of PPi and fru-2,6-P2. Similarly, concentration of UDP-glucose was higher than that of ADP-glucose. Based on these results, it is proposed that the major role of the enzyme PFP in developing wheat grain is to provide PPi for sucrose breakdown via sucrose synthase.

Alteraçöes enzimáticas eritrocitárias na hemofilia A / Erythrocyte enzymatic changes in hemophilia A

Cinco quinases eritrocitárias foram estudadas em pacientes portadores de hemofilia A; foi encontrado um aumento das atividades da fosfogliceratoquinase e da adenilatoquinase. Este achado sugere que há alteraçöes metabólicas eritrocitárias na hemofilia