TNF-alpha acts in the hypothalamus inhibiting food intake and increasing the respiratory quotient - Effects on leptin and insulin signaling pathways

Acting in the hypothalamus, tumor necrosis factor-alpha (TNF-alpha) produces a potent anorexigenic effect. However, the molecular mechanisms involved in this phenomenon are poorly characterized. In this study, we investigate the capacity of TNF-alpha to activate signal transduction in the hypothalamus through elements of the pathways employed by the anorexigenic hormones insulin and leptin. High dose TNF-a promotes a reduction of 25% in 12 h food intake, which is an inhibitory effect that is marginally inferior to that produced by insulin and leptin. In addition, high dose TNF-a increases body temperature and respiratory quotient, effects not reproduced by insulin or leptin. TNF-alpha, predominantly at the high dose, is also capable of activating canonical pro-inflammatory signal transduction in the hypothalamus, inducing JNK, p38, and NF kappa B, which results in the transcription of early responsive genes and expression of proteins of the SOCS family. Also, TNF-a activates signal transduction through JAK-2 and STAT-3, but does not activate signal transduction. through early and intermediary elements of the insulin/leptin signaling pathways such as IRS-2, Akt, ERK and FOXO1. When co-injected with insulin or leptin, TNF-a, at both high and low doses, partially impairs signal transduction through IRS-2, Akt, ERK and FOXO1 but not through JAK-2 and STAT-3. This effect is accompanied by the partial inhibition of the anorexigenic effects of insulin and leptin, when the low, but not the high dose of TNF-alpha is employed. In conclusion, TNF-alpha, on a dose-dependent way, modulates insulin and leptin signaling and action in the hypothalamus. (c) Published by Elsevier B.V.

Inhibition of 5-alpha-reductase activity induces stromal remodeling and smooth muscle de-differentiation in adult gerbil ventral prostate

Prostatic differentiation during embryogenesis and its further homeostatic state maintenance during adult life depend on androgens. Dihydrotestosterone, which is synthesized from testosterone by 5alpha-reductase (5alpha-r), is the active molecule triggering androgen action within the prostate. In the present work, we examined the effects of 5alpha-reductase inhibition by finasteride in the ventral prostate (VP) of the adult gerbil, employing histochemical and electron microscopy techniques to demonstrate the morphological and organizational changes of the organ. After 10 days of finasteride treatment at a dose of 100 mg/kg/day, the prostatic complex (VP and dorsolateral prostate) absolute weight was reduced to about 18%. The epithelial cells became short and cuboidal, with less secretory blebs and reduced acid phosphatase activity. The luminal sectional area diminished, suggestive of decreased secretory activity. The stromal/epithelial ratio increased, the stroma becoming thicker but less cellular. There was a striking accumulation of collagen fibrils, which was accompanied by an increase in deposits of amorphous granular material adjacent to the basal lamina and in the clefts between smooth muscle cells (SMC). Additionally, the periacinar smooth muscle became loosely packed. Some SMC were atrophic and showed a denser array of the cytoskeleton, whereas other SMC had a highly irregular outline with numerous spine-like projections. The present data indicate that 5alpha-r inhibition causes epithelial and stromal changes by affecting intra-prostatic hormone levels. These alterations are probably the result of an imbalance of the homeostatic interaction between the epithelium and the underlying stroma.

Alternative method of smearing samples on slides facilitate visualization of hemoglobin H inclusion bodies in alpha thalassemia

Nas talassemias alfa, a HbH pode ser detectada, nos eritrócitos do sangue periférico como inclusões celulares quando coradas com azul crezil brillante. Este teste simples é útil para o diagnóstico de talassemia alfa, no entanto, a identificação dos corpos de inclusão de HbH é um processo laborioso e os resultados são altamente dependentes do observador. No intuito de melhorar a identificação das inclusões, foi testado um método alternativo para espalhar as amostras nas lâminas. Amostras de sangue foram espalhadas nas lâminas usando-se o método clássico e o método alternativo. O método alternativo permitiu uma melhor identificação das inclusões de HbH do que o método clássico. Nossos resultados mostraram que o método alternativo é uma opção útil para a pesquisa dos corpúsculos de inclusão de HbH naquelas amostras onde o método clássico não o permite.

A rapid technique for analysis of formalin-fixed, paraffin-embedded tissues by fluorescent in situ hybridization with alpha-satellite probes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Purification and Characterization of the alpha-Glucosidase Produced by Thermophilic Fungus Thermoascus aurantiacus CBMAI 756

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Increased Androgen Receptor and Remodeling in the Prostatic Stroma After the Inhibition of 5-Alpha Reductase and Aromatase in Gerbil Ventral Prostate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Long-term inhibition of 5-alpha reductase and aromatase changes the cellular and extracellular compartments in gerbil ventral prostate at different postnatal ages

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Oxidative Stability and alpha-Tocopherol Retention in Soybean Oil with Lemon Seed Extract (Citrus Limon) under Thermoxidation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Initial structural analysis of an alpha(4)beta(4) C-type lectin from the venom of Crotalus durissus terrificus

Convulxin, an alphabeta C-type lectin, is a potent platelet activator isolated from the venom of the South American rattlesnake Crotalus durissus terrificus. It is a 26.5 kDa alphabeta heterodimer consisting of two homologous disulfide-linked chains. The crystals belong to space group I4, with unit-cell parameters a = b = 131.61, c = 121.85 Angstrom, and diffraction data were collected to 2.7 Angstrom. The structure was solved by molecular replacement and the asymmetric unit contains two alphabeta heterodimers, each of which forms a disulfide-linked cyclic alpha(4)beta(4) tetramer in the unit cell. These alpha(4)beta(4) tetramers are stacked to form a large solvent channel.

Tertiary structural changes of the alpha-hemolysin from Staphylococcus aureus on association with liposome membranes

The interaction of alpha-hemolysin (also called alpha-toxin) from Staphylococcus aureus with mixed egg-yolk phosphatidylcholine/cholesterol liposomes has been investigated using the intrinsic tryptophan fluorescence emission (ITFE) signal. The ITFE intensity of alpha-hemolysin, which was obtained using a novel purification protocol, showed a triphasic increase on incubation with liposomes at low protein/lipid ratios. The first, rapid phase results in an increase in ITFE of 10%, which reflects rapid conformation changes in the alpha-hemolysin on association with the liposome membrane, the second phase of the ITFE increase is associated with a red shift from 334 to 339 nm in the maximum emission wavelength, suggesting the transition to a partially unfolded intermediate in the oligomerization process. The third phase of the ITFE intensity change demonstrates a temporal correlation with the appearance of SDS-stable oligomers. The results demonstrate the feasibility of identification of intermediate protein conformations in complex membrane-associated processes by manipulation of the liposomal membrane composition. (C) 1998 Academic Press.

A stability transition at mildly acidic pH in the alpha-hemolysin (alpha-toxin) from Staphylococcus aureus

The effects of mildly acidic conditions on the free energy of unfolding (Delta G(u)(buff)) of the pore-forming alpha-hemolysin (alpha HL) from Staphylococcus aureus were assessed between pH 5.0 and 7.5 by measuring intrinsic tryptophan fluorescence, circular dichroism and elution time in size exclusion chromatography during urea denaturation, Decreasing the pH from 7.0 to 5.0 reduced the calculated Delta G(u)(buff) from 8.9 to 4.2 kcal moI(-1), which correlates with an increased rate of pore formation previously observed over the same pH range, It is proposed that the lowered surface pH of biological membranes reduces the stability of alpha HL thereby modulating the rate of pore formation. (C) 1999 Federation of European Biochemical Societies.

Crystal structure of the platelet activator convulxin, a disulfide-linked alpha(4)beta(4) cyclic tetramer from the venom of Crotalus durissus terrificus

Convulxin (CVX), a C-type lectin, isolated from the venom of the South American rattlesnake Crotalus durissus terrificus, causes cardiovascular and respiratory disturbances and is a potent platelet activator which hinds to platelet glycoprotein GPVI. The structure of CVX has been solved at 2.4 Angstrom resolution to a crystallographic residual of 18.6% (R-free =26.4%). CVX is a disulfide linked heterodimer consisting of homologous alpha and beta chains. The heterodimers are additionally linked by disulfide bridges to form cyclic alpha(4)beta(4)heterotetramers. These domains exhibit significant homology to the carbohydrate-binding domains of C-type lectins, to the factor IX-binding protein (IX-bp), and to flavocetin-A (Fl-A) but sequence and Structural differences are observed in both the domains in the putative Ca2+ and carbohydrate binding regions. (C) 2003 Elsevier B.V. All rights reserved.

Structural studies of BmooMP alpha-I, a non-hemorrhagic metalloproteinase from Bothrops moojeni venom

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)