Preparation of nanocomposites resin from seed Pterodon emarginatus doped maghemite nanoparticles.

Electrical characterization and magnetic nanocomposite resin seeds Pterodon emarginatus (PE) doped with nanoparticles of maghemite and treated by different chemical processes is reported in this paper. The pure PE resin showed semiconducting characteristics probably the presence of natural iron oxide in its molecular structure. The analysis of Mössbauer spectra pure resin showed two magnetic sites presented on measurements made at temperature of 300 K. Six "LEDs" to have been doped maghemite nanoparticles forming concentrations of 2.6 x 10(15) to 1.56 x 10(16) particles/cm2 forming the LED-PEMN. In the presence of the applied current versus voltage (0 to 0.9 V) LED-PEMN shown semiconducting properties. In the presence of frequency versus voltage sample of pure resin and LED features small decrease. While samples of LED-PEMN suffers loss frequency linearly with concentration and voltage. The pure PE resin shows high resistance to the applied voltage while the LED-PEMN is observed linear increase with the strength and concentration of nanoparticles of maghemite.

The role of transjugular liver biopsy in a liver transplant center.

Transjugular liver biopsy is a particularly useful procedure in overcoming the classic limitations of percutaneous biopsy, such as hemorrhagic diathesis or tense ascites. The authors evaluated the impact that this technique had in their liver transplant program, considering performance and safety in 160 procedures. Histologic characterization was accomplished in 75% of cirrhotic patients and in 96% of patients with acute liver disease. Confirmation of a presumptive diagnosis was made in 76% of patients and a previously unsuspected diagnosis was raised in 11%. Hemochromatosis, Wilson's disease, and acute alcoholic hepatitis were the most challenging diagnoses and, together with patients with liver failure, had the most relevant implications in transplant decisions. The availability of transjugular liver biopsy provided decisive information regarding patient selection and the best timing to proceed with transplantation.

Searching for the role of protein phosphatases in eukaryotic microorganisms.

Preference for specific protein substrates together with differential sensitivity to activators and inhibitors has allowed classification of serine/threonine protein phosphatases (PPs) into four major types designated types 1, 2A, 2B and 2C (PP1, PP2A, PP2B and PP2C, respectively). Comparison of sequences within their catalytic domains has indicated that PP1, PP2A and PP2B are members of the same gene family named PPP. On the other hand, the type 2C enzyme does not share sequence homology with the PPP members and thus represents another gene family, known as PPM. In this report we briefly summarize some of our studies about the role of serine/threonine phosphatases in growth and differentiation of three different eukaryotic models: Blastocladiella emersonii, Neurospora crassa and Dictyostelium discoideum. Our observations suggest that PP2C is the major phosphatase responsible for dephosphorylation of amidotransferase, an enzyme that controls cell wall synthesis during Blastocladiella emersonii zoospore germination. We also report the existence of a novel acid- and thermo-stable protein purified from Neurospora crassa mycelia, which specifically inhibits the PP1 activity of this fungus and mammals. Finally, we comment on our recent results demonstrating that Dictyostelium discoideum expresses a gene that codes for PP1, although this activity has never been demonstrated biochemically in this organism.

Searching for the role of protein phosphatases in eukaryotic microorganisms

Preference for specific protein substrates together with differential sensitivity to activators and inhibitors has allowed classification of serine/threonine protein phosphatases (PPs) into four major types designated types 1, 2A, 2B and 2C (PP1, PP2A, PP2B and PP2C, respectively). Comparison of sequences within their catalytic domains has indicated that PP1, PP2A and PP2B are members of the same gene family named PPP. On the other hand, the type 2C enzyme does not share sequence homology with the PPP members and thus represents another gene family, known as PPM. In this report we briefly summarize some of our studies about the role of serine/threonine phosphatases in growth and differentiation of three different eukaryotic models: Blastocladiella emersonii, Neurospora crassa and Dictyostelium discoideum. Our observations suggest that PP2C is the major phosphatase responsible for dephosphorylation of amidotransferase, an enzyme that controls cell wall synthesis during Blastocladiella emersonii zoospore germination. We also report the existence of a novel acid- and thermo-stable protein purified from Neurospora crassa mycelia, which specifically inhibits the PP1 activity of this fungus and mammals. Finally, we comment on our recent results demonstrating that Dictyostelium discoideum expresses a gene that codes for PP1, although this activity has never been demonstrated biochemically in this organism

Pitiose cutânea em eqüídeos no semi-árido da Paraíba / Cutaneous pythiosos in horses and mules in Paraíba, Brazil

Entre os anos de 1986 e 1996, foram estudadas lesöes cutâneas em 35 eqüinos e três muares, provenientes do município de Patos-Paraíba e regiöes circunvizinhas. As lesöes tinham localizaçäo e tamanho variados com características granulomatosas e ulceradas, com secreçäo serossangüinolenta e concreçöes amareladas de consistência firme e aspecto de coral marinho (kunkers). Para o diagnóstico definitico de pitiose utilizaram-se exames histopatológicos, cultura e identificaçäo do agente

Serine/threonine protein phosphatases and a protein phosphatase 1 inhibitor from Neurospora crassa.

The major spontaneously active serine/threonine (Ser/Thr) protein phosphatase activities in N. crassa wild type (FGSC 424) were type-1 (PP1), type-2A (PP2A) and type-2C (PP2C). PP1 and PP2C predominantly dephosphorylated phosphorylase a and casein, respectively. PP2A acted on both substrates, but was two-fold more active against casein. PP1 activity was inhibited by protamine, heparin, okadaic acid (IC50 50 nM) and mammalian inhibitor-1 (IC50 2 nM). On the other hand. PP2A activity was inhibited by much lower concentrations of okadaic acid (IC50 0.2 nM) and also by protamine, but not by heparin or inhibitor-1. About 80% of total PP1 activity was associated with the particulate fraction and could be partially extracted with 0.5 M NaCl. Seventy and ninety percent of PP2A and PP2C activities, respectively, were found in the soluble fraction. In addition we have partially purified an acid and thermostable PP1 inhibitor which effectively inhibits both N. crassa and mammalian PP1.

Serine/threonine protein phosphatases and a protein phosphatase 1 inhibitor from Neurospora crassa

The major spontaneously active serine/threonine (Ser/Thr) protein phosphatase activities in N. crassa wild type (FGSC 424) were type 1 (PP1), type-2A (PP2A) and type-2C (PP2C). PP1 and PP2C predominantly dephosphorylated phosphorylase a and casein, respectively. PP2A acted on both substrates, but was two-fold more active against casein. PPI activity was inhibited by protamine, heparin, okadaic acid (IC50 50 nM) and mammalian inhibitor- 1 (lC50 2 nM). On the other hand, PP2A activity was inhibited by much lower concentrations of okadaic acid (IC50 0.2 nM) and also by protamine, but not by heparin or inhibitor-l. About 80 per cent of total PP1 activity was associated with the particulate fraction and could be partially extracted with 0.5 M NaCl. Seventy and ninety percent of PP2A and PP2C activities, respectively, were found in the soluble fraction. In addition we have partially purified an acid and thermostable PP1 inhibitor which effectively inhibits both N. crassa and mammalian PP1.

Calcium uptake and gp80 messenger RNA destabilization follows cAMP receptor down regulation in Dictyostelium discoideum.

The mechanism by which high concentrations of cAMP selectively destabilize the gp80 mRNA in Dictyostelium discoideum was investigated. This treatment which leads to down-regulation of the cAMP receptor was also found to cause an increase in calcium uptake. Given this observation, we sought a role for calcium as a second messenger in the degradation of the gp80 mRNA. Changes in the mRNA levels were examined after treating cells with compounds known to alter their intracellular Ca2+ concentrations. This included the use of A23187, Ca2+, 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate HC1 (TMB-8), LiCl and 8-p-chlorophenylthioadenosine 3',5'-cyclic monophosphate (ClPhS-Ado-3':5'-P). The sum of the data suggest that it is the cAMP-induced influx of Ca2+ across the plasma membrane, as apposed to a cAMP-mediated release of Ca2+ from intracellular stores, that initiates gp80 mRNA degradation. Treatment of cells with Concanavalin A (ConA) to induce cAMP receptor down-regulation, also causes a reduction in gp80 mRNA levels and an increase in calcium uptake.

Hexosamine and cell wall biogenesis in the aquatic fungus Blastocladiella emersonii.

Chitin, a beta-(1-->4) polymer of N-acetyl-glucosamine, is an important constituent of fungal cell walls. This polymer is synthesized by the incorporation of N-acetyl-D-glucosamine units from the precursor UDP-N-acetyl-D-glucosamine (UDP-GlcNAc) in a reaction catalyzed by chitin synthase. In the aquatic fungus Blastocladiella emersonii, chitin, the major component of the cell wall, is synthesized and incorporated in the cell surface of the free-swimming zoospore during the abrupt transition from this wall-less cell to the sessile, wall-containing cyst. Studies with cycloheximide indicate that chitin synthesis occurs in the apparent absence of protein synthesis, and thus posttranslational controls presumably regulate the cell wall biogenesis during encystment. Glutamine: fructose 6-phosphate amidotransferase, first enzyme of the hexosamine biosynthetic pathway, was found to play a central role in the regulation of chitin synthesis in this fungus. This enzyme exists in two forms, which are interconvertible by phosphorylation or dephosphorylation of serine residues. It is allosterically inhibited in the phosphorylated form, as it is in the zoospore, by UDP-GlcNAc. In addition, UDP-GlcNAc inhibits the dephosphorylation of amidotransferase catalyzed by protein phosphatases 2A and 2C. Thus, UDP-GlcNAc plays a dual role in hexosamine and chitin synthesis in zoospore: it not only inhibits the phosphorylated form of the enzyme but also prevents its dephosphorylation. The available data suggest that substrate availability plays a role in the control of chitin synthesis during zoospore differentiation.

[The risk of diabetes mellitus in relatives of diabetics treated with insulin]. / Risco de diabetes mellitus em familiares de diabéticos tratados com insulina.

The objective of this study was to compare the risk of diabetes mellitus in the relatives of type 1 (defined as cases diagnosed before 40 years and beginning insulin less than two years later) and in those of type 2 diabetics, treated with insulin. A random sample of 303 patients was obtained from responders to a postal survey sent to all 2800 diabetics living in the Oporto self county and identified as users of insulin the injection pen. After selecting those who completed the questions for sex, age, dates of diabetes diagnosis and of first insulin prescription, we were left with 192 index cases. They provided data concerning sex; age, and presence of diabetes for 1370 relatives (parents, siblings, offspring and spouses). The risk of diabetes (unspecified type) in family members was significantly lower in relatives of type 1 diabetics (OR = 0.31, CI 95%:0.19-0.48, p < 0.0005). This family risk was lower when the index case was a male (OR = 0.24, CI 95%:0.12-0.47 vs OR = 0.39, CI 95%:0.21-0.74) or for female relatives (OR = 0.22, CI 95%:0.11-0.42 vs OR = 0.43, CI 95%:0.22.-0.82). After adjustment for confounders applying logistic regression to each family stratum, the risk remained significantly lower for parents (OR = 0.35, CI 95%:0.17-0.71) and siblings of type 1 diabetics compared to similar relatives of type 2 cases (OR = 0.84, CI 95%:0.06-10.6) but was not significantly different for the offspring (OR = 0.68, CI 95%:0.11-4.17) or the spouses (OR = 0.84, CI 95%:0.06-10.6).(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of adenylyl cyclase from Blastocladiella emersonii by guanine nucleotides.

GTP gamma S stimulates adenylyl cyclase in particulate fractions of Blastocladiella emersonii zoospores. Cholera toxin catalyses the ADP-ribosylation of a membrane protein of a molecular weight (46,000) similar to that of the alpha subunit of Gs found in vertebrate cells. A membrane protein of 46 kDa can also be recognized in Western blots by an antipeptide antiserum (RM/1) raised against the C-terminus of G alpha 2-subunits. These results suggest that a G-protein mediates the regulation of Blastocladiella adenylyl cyclase by guanine nucleotides.

Developmental regulation of hexosamine biosynthesis by protein phosphatases 2A and 2C in Blastocladiella emersonii.

Extracts of the aquatic fungus Blastocladiella emersonii were found to contain protein phosphatases type 1, type 2A, and type 2C with properties analogous to those found in mammalian tissues. The activities of all three protein phosphatases are developmentally regulated, increasing during sporulation, with maximum level in zoospores. Protein phosphatases 2A and 2C, present in zoospore extracts, catalyze the dephosphorylation of L-glutamine:fructose-6-phosphate amidotransferase (EC 2.6.1.16, amidotransferase), a key regulatory enzyme in hexosamine biosynthesis. The protein phosphatase inhibitor okadaic acid induces encystment and inhibits germ tube formation but does not affect the synthesis of the chitinous cell wall. These results strongly suggest that phosphatase 2C is responsible for the dephosphorylation of amidotransferase in vivo. This dephosphorylation is inhibited by uridine-5'-diphospho-N-acetylglucosamine, the end product of hexosamine synthesis and the substrate for chitin synthesis. This result demonstrates a dual role of uridine-5'-diphospho-N-acetylglucosamine by inhibiting the activity of the phosphorylated form of amidotransferase and by preventing its dephosphorylation by protein phosphatases.

Serine/threonine protein phosphatases in Dictyostelium discoideum: no evidence for type I activity.

Extracts from Dictyostelium discoideum contain type 2A and 2C serine/threonine-specific protein phosphatases with properties very similar to those from mammals according to their sensitivity to okadaic acid and to their dependence for divalent cations. In contrast, no type 1 protein phosphatase is found at any time of development, neither in the cytosolic nor in the particulate fraction, using glycogen phosphorylase a, casein, histone or the non-proteinous 4-Methylumbelliferyl phosphate as substrates. Both type 2A and 2C protein phosphatase activities remain constant throughout the development cycle.

Childhood asthma and outdoor air pollution in Oporto area.

The influence of outdoor air pollution, on childhood asthma, is not yet completely understood, especially a long exposition to low but persistent pollutants levels. This paper presents the relationship between air pollution, as sulphur dioxide (SO2) and black smoke (BS), and asthmatic attacks on children living in the Oporto area, during the period between 1983 and 1987, when its levels ranged below the official "security" ones. There was no correlation between daily levels of SO2 or BS, and the asthmatic attacks rate. However, for longer periods, as months and quarters, an increased positive correlation was found, but only with SO2 (r = 0.334, p = 0.01; r = 0.473, p = 0.07, for month and quarter periods, respectively). These data suggest that, neither SO2 nor BS seem to be direct bronchospasm inductors, at least when its levels stay between the relatively low limits observed. On the other hand, the longer exposition to SO2 appears to lower the threshold of the asthmatic children to other bronchospasm stimulus.

Fructose 2,6-bisphosphate and carbohydrate metabolism during the life cycle of the aquatic fungus Blastocladiella emersonii.

Removal of the growth medium and resuspension of Blastocladiella emersonii vegetative cells in a sporulation medium resulted in an abrupt fall of fructose 2,6-bisphosphate concentration to about 2% of its initial value within 10 min. The concentrations of hexose 6-phosphate and of fructose 1,6-bisphosphate also decreased by, respectively, three and tenfold over the same period. All these values remained at their low level throughout the sporulation phase and during the subsequent germination of zoospores when performed in the absence of glucose. In contrast, the concentration of cyclic AMP was low during the sporulation period and exhibited a transient increase a few minutes after the initiation of germination. Other biochemical events occurring during sporulation were a 70% reduction in glycogen content and the complete disappearance of trehalose. The remaining glycogen was degraded upon subsequent germination of the zoospores. B. emersonii phosphofructo 2-kinase (PFK-2) and fructose-2,6-bisphosphatase (FBPase-2) could not be separated from each other by various chromatographic procedures, suggesting that they were part of a single bifunctional protein. On anion-exchange chromatography, two peaks of PFK-2 and FBPase-2 were resolved. Upon incubation of fractions from the two peaks or of a crude extract in the presence of [2-32P]fructose 2,6-bisphosphate, two radiolabelled subunits with molecular masses close to 90 and 54 kDa were obtained. The labelling of the subunit of higher molecular mass was greater than that of the lower one in extracts prepared in the presence of protease inhibitors and in the first peak of the Mono Q column. PFK-2 and FBPase-2 displayed kinetic properties comparable to those of mammalian enzymes, but no indication of a cyclic AMP-dependent regulation could be obtained. Phosphofructo 1-kinase and fructose-1,6-bisphosphatase from B. emersonii were, respectively, stimulated and inhibited by micromolar concentrations of fructose 2,6-bisphosphate. The physiological significance of these properties is discussed. A simple method for the determination of trehalose is also reported.