Comparison of non-Ohmic accelerated ageing of the ZnO- and SnO2-based voltage dependent resistors

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

Chemically induced immunotoxicity in a medium-term multiorgan bioassay for carcinogenesis with Wistar rats

A variety of chemicals can adversely affect the immune system and influence tumor development. The modifying potential of chemical carcinogens on the lymphoid organs and cytokine production of rats submitted to a medium-term initiation-promotion bioassay for carcinogenesis was investigated. Male Wistar rats were sequentially initiated with N-nitrosodiethylamine (DEN), N-methyl-N-nitrosourea (MNU), N-butyl-N-(4hydroxybutyl)nitrosamine (BBN), dihydroxy-di-n-propylnitrosamine (DHPN), and 1,2-dimethylhydrazine (DMH) during 4 weeks. Two initiated groups received phenobarbital (PB) or 2-acetyl amino fluorene (2-AAF) for 25 weeks and two noninitiated groups received only PB or 2-AAF. A nontreated group was used as control. Lymphohematopoietic organs, liver, kidneys, lung, intestines, and Zymbal's gland were removed for histological analysis. Interleukin (IL)-2, IL-12, interferon gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), IL-10, and transforming growth factor betal (TGF-beta1) levels were determined by ELISA in spleen cell culture supernatants. At the fourth week, exposure to the initiating carcinogens resulted in cell depletion of the thymus, spleen and bone marrow, and impairment of IL-2, IL-12, and IFN-gamma production. However, at the 30th week, no important alterations were observed both in lymphoid organs and cytokine production in the different groups. The results indicate that the initiating carcinogens used in the present protocol exert toxic effects on the lymphoid organs and affect the production of cytokines at the initiation step of carcinogenesis. This early and reversible depression of the immune surveillance may contribute to the survival of initiated cells facilitating the development of future neoplasia. (C) 2003 Elsevier B.V. All rights reserved.

Cytotoxicity and Regenerative Proliferation as the Mode of Action for Diuron-Induced Urothelial Carcinogenesis in the Rat

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

Ação neuro-muscular do veneno crotálico: dados preliminares

Estudamos 6 pacientes, 2 cães e um coelho com intoxicação crotálica. Avaliamos a condução nervosa periférica sensitiva e motora, a transmissão neuromuscular e eletromiografias. As biópsias de músculo foram processadas por histoquímica. Os 6 pacientes apresentaram mononeuropatia sensitiva no nervo periférico adjacente ao local da inoculação do veneno e encontramos evidências histoquímicas de miopatia mitocondrial. Os defeitos da transmissão neuromuscular foram mínimos. A maioria dos autores admite que veneno crotálico determina síndrome miastênica. Nossos achados indicam que ptose palpebral, facies miastênico e fraqueza muscular observados após acidente crotálico, correspondem provavelmente a miopatia mitocondrial, muitas vezes transitória e reversível.

Óxido nítrico inalatório para crianças com síndrome do desconforto respiratório agudo

JUSTIFICATIVA E OBJETIVOS: O objetivo desse estudo foi rever a literatura sobre a utilização de óxido nítrico inalatório em crianças com síndrome do desconforto respiratório agudo. CONTEÚDO: Revisão bibliográfica e seleção de publicações mais relevantes sobre óxido nítrico inalatório, utilizando a base de dados MedLine e Cochrane de Revisões Sistemáticas. A revisão incluiu descrição de aspectos da definição, fisiopatologia e tratamento ventilatório da síndrome do desconforto respiratório agudo, assim como o metabolismo, efeitos biológicos e aplicação clínica do óxido nítrico inalatório, comentando dose, administração e retirada do gás, precações, efeitos adversos e contra-indicações. CONCLUSÕES: O óxido nítrico, vasodilatador pulmonar seletivo, tem efeitos benéficos sobre as trocas gasosas e ventilação em crianças com hipóxia grave. É seguro quando administrado em ambiente de tratamento intensivo sob rigorosa monitorização. Estudos aleatórios e controlados devem enfocar a administração precoce do gás na síndrome do desconforto respiratório agudo, quando essa é potencialmente reversível.

Cell-mediated immune response to Leishmania chagasi experimental infection of BALB/c immunosuppressed mice

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

Ovarian activity reversibility after the use of deslorelin acetate as a short-term contraceptive in domestic queens

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

Oral rehabilitation of severely worn dentition using an overlay for immediate re-establishment of occlusal vertical dimension

The aim of this study was to describe the treatment used in an elderly patient presenting with bruxism and dental erosion, with good gingival health and bone support, but with decreased occlusal vertical dimension (OVD). The oral rehabilitation of elderly patients presenting with bruxism in association with tooth erosion has been a great challenge for dentists. The loss of OVD, the presence of occlusal instability and the absence of an effective anterior guide due excessive dental wear, can damage stomatognathic system (SS) biology, the function and the aesthetics. In the first treatment stage, an overlay removable partial denture (ORPD) was fabricated for the immediate re-establishment of function and aesthetics. After a 2-month follow up, with the patient presenting no symptoms, a second rehabilitation stage was accomplished, with fixed and removable prostheses. Oral rehabilitation with an ORPD was able to re-establish the SS biology, but a correct diagnosis and treatment plan are essential for success. The ORPD is a non-invasive and reversible restoring modality for general dentists that allow the re-establishment of the patient's immediate aesthetics and function at low cost.

Ischaemia and reperfusion effects on skeletal muscle tissue: morphological and histochemical studies

This was a study on the oxidative stress due to ischaemia (I) and reperfusion (R) in skeletal muscle tissue. Using a tourniquet, groups of rats were submitted to ischaemia for 4 h, followed by different reperfusion periods. The animals were divided in four groups: control; 4 h of ischaemia (IR); 4 h of ischaemia plus 1 h reperfusion (IR-1 h); 4 h of ischaemia plus 24 h reperfusion (IR-24 h); and 4 h of ischaemia plus 72 h reperfusion (IR-72 h). At the end of the procedures, samples of soleus muscle were collected and frozen in n-hexane at -70 degrees C. Cryostat sections were submitted to haematoxylin-eosin, succinate dehydrogenase (SDH) and nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR) stains. An additional muscle sample was processed for electron microscopy. No alterations were found in control animals. IR group showed fibres had normal aspect besides some round, acidophilic and hypertrophic fibres. There were several fibres with angular outlines and smaller diameters in this group compared with control group. NADH-TR/SDH reaction was moderately intense in most fibres. In some fibres, cytoplasm showed areas without activity and other fibres had very intense reactivity. IR-1 h group showed oedema hypercontracted fibres with disorganized myofibrils, mitochondria with focal lesions and dilated sarcoplasmic reticulum. NADH-TR/SDH reaction was moderate to weak. IR-24 h showed intense inflammatory infiltrate in the endomysium and perimysium. NADH-TR/SDH reaction was similar to IR-1 h. IR-72 h showed necrotic fibres, areas with inflammatory infiltrate, reduced muscle fibres at different stages of necrosis and phagocytosis, and many small round and basophilic fibres characterizing a regeneration process. NADH-TR/SDH reaction was weak to negative. Our results suggest that ischaemia and the subsequent 1-, 24- and 72-h reperfusions induced progressive histological damage. Although progressive, it may be reversible because there were ultrastructural signs of recovery after 72-h reperfusion. This recovery could in part be due to the low oxidative stress identified by the morphological and histochemical analysis.

Antineoplasic Drug Methotrexate Redox Mechanism Using a Glassy Carbon Electrode

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Docking and small angle X-ray scattering studies of purine nucleoside phosphorylase

Docking simulations have been used to assess protein complexes with some success. Small angle X-ray scattering (SAXS) is a well-established technique to investigate protein spatial configuration. This work describes the integration of geometric docking with SAXS to investigate the quaternary structure of recombinant human purine nucleoside phosphorylase (PNP). This enzyme catalyzes the reversible phosphorolysis of N-ribosidic bonds of purine nucleosides and deoxynucleosides. A genetic deficiency due to mutations in the gene encoding for PNP causes gradual decrease in T-cell immunity. Inappropriate activation of T-cells has been implicated in several clinically relevant human conditions such as transplant rejection, rheumatoid arthritis, lupus, and T-cell lymphomas. PNP is therefore a target for inhibitor development aiming at T-cell immune response modulation and has been submitted to extensive structure-based drug design. The present analysis confirms the trimeric structure observed in the crystal. The potential application of the present procedure to other systems is discussed. (C) 2003 Elsevier B.V. All rights reserved.

The kinetic mechanism of human uridine phosphorylase 1: Towards the development of enzyme inhibitors for cancer chemotherapy

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of Spider Venom Toxin PWTX-I (6-Hydroxytrypargine) on the Central Nervous System of Rats

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

LEAST ACTION PRINCIPLE and THE INCOMPRESSIBLE EULER EQUATIONS WITH VARIABLE DENSITY

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

Spinning Hopf solitons on S-3 x R

We consider a field theory with target space being the two dimensional sphere S-2 and defined on the space-time S-3 x R. The Lagrangean is the square of the pull-back of the area form on S-2. It is invariant under the conformal group SO(4, 2) and the infinite dimensional group of area preserving diffeomorphisms of S-2. We construct an infinite number of exact soliton solutions with non-trivial Hopf topological charges. The solutions spin with a frequency which is bounded above by a quantity proportional to the inverse of the radius of S-3. The construction of the solutions is made possible by an ansatz which explores the conformal symmetry and a U(1) subgroup of the area preserving diffeomorphism group.