Dielectric and impedance properties of Nd3/2Bi3/2Fe5O12 ceramics

The polycrystalline sample of Nd3/2Bi3/2Fe5O12 was prepared by a high- temperature solid-state reaction technique. Preliminary X-ray structural analysis exhibits the formation of a single-phase tetragonal structure at room temperature. Microstructural analysis by scanning electron microscopy shows that the sintered sample has well defined grains. These grains are distributed uniformly throughout the surface of the sample. Detailed studies of dielectric response at various frequencies and temperatures exhibit a dielectric anomaly at 400 A degrees C. The electrical properties (impedance, modulus and conductivity) of the material were studied using a complex impedance spectroscopy technique. These studies reveal a significant contribution of grain and grain boundary effects in the material. The frequency dependent plots of modulus and the impedance loss show that the conductivity relaxation is of non-Debye type. Studies of electrical conductivity with temperature demonstrate that the compound exhibits Arrhenius-type of electrical conductivity. Study of ac conductivity with frequency suggests that the material obeys Jonscher's universal power law.

IMPEDANCE CHARACTERISTICS of La3/2Bi3/2Fe5O12 CERAMICS

Polycrystalline La3/2Bi3/2Fe5O12 (LBIO) compound was prepared by a high-temperature solid-state reaction technique. The complex impedance of LBIO was measured over a wide temperature (i.e., room temperature to 500 C) and frequencies (i.e., 10(2)-10(6) Hz) ranges. This study takes advantage of plotting ac data simultaneously in the form of impedance and modulus spectroscopic plots and obey non-Debye type of relaxation process. The Nyquist's plot showed the presence of grain effects in the material at high temperature. The ac conductivity spectrum was found to obey Jonscher's universal power law. The dc conductivity was found to increase with rise in temperature. The activation energy of the compound was found to be 0.24 and 0.51 eV in the low and high-temperature region, respectively, for conduction process.

AC Conductivity and Impedance Properties of 0.65Pb(Mg1/3Nb2/3)O-3-0.35PbTiO(3) Ceramics

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

Lymphocyte transformation assay for C neoformans antigen is not reliable for detecting cellular impairment in patients with Neurocryptococcosis

Background: Cryptococcus neoformans causes meningitis and disseminated infection in healthy individuals, but more commonly in hosts with defective immune responses. Cell-mediated immunity is an important component of the immune response to a great variety of infections, including yeast infections. We aimed to evaluate a specific lymphocyte transformation assay to Cryptococcus neoformans in order to identify immunodeficiency associated to neurocryptococcosis (NCC) as primary cause of the mycosis.Methods: Healthy volunteers, poultry growers, and HIV-seronegative patients with neurocryptococcosis were tested for cellular immune response. Cryptococcal meningitis was diagnosed by India ink staining of cerebrospinal fluid and cryptococcal antigen test (Immunomycol-Inc, SP, Brazil). Isolated peripheral blood mononuclear cells were stimulated with C. neoformans antigen, C. albicans antigen, and pokeweed mitogen. The amount of H-3-thymidine incorporated was assessed, and the results were expressed as stimulation index (SI) and log SI, sensitivity, specificity, and cut-off value (receiver operating characteristics curve). We applied unpaired Student t tests to compare data and considered significant differences for p<0.05.Results: The lymphotoxin alpha showed a low capacity with all the stimuli for classifying patients as responders and non-responders. Lymphotoxin alpha stimulated by heated-killed antigen from patients with neurocryptococcosis was not affected by TCD4+ cell count, and the intensity of response did not correlate with the clinical evolution of neurocryptococcosis.Conclusion: Response to lymphocyte transformation assay should be analyzed based on a normal range and using more than one stimulator. The use of a cut-off value to classify patients with neurocryptococcosis is inadequate. Statistical analysis should be based on the log transformation of SI. A more purified antigen for evaluating specific response to C. neoformans is needed.

Pancreas transplantation prevents cellular oxidative stress in kidneys of alloxan-induced diabetic rats

Purpose. Oxidative stress is one of the most important mechanisms to explain genesis of the complications in the chronic progression of diabetes. In this investigation we studied the effects of pancreas transplantation (PT) on the imbalance caused by excessive production of free oxygen radicals by antioxidant defenses of rats with serious chronic hyperglycemia induced by alloxan.Methods. Ninety inbred male Lewis rats were randomly distributed into three groups: NC-30 nondiabetic controls; DC-30 diabetic controls without any treatment; PT-30 diabetic rats undergoing syngeneic PT from normal donor Lewis rats. Each experimental group was then split into three subgroups of 10 animals for sacrifice after 1, 3, or 6 months. Clinical and laboratory parameters from all rats as well as lipid hydroperoxide (LPO) concentrations and renal tissue enzyme activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were recorded for all rats.Results. Successful PT corrected clinical and laboratory alterations in diabetic rats with sustained normoglycemia throughout the study. A significant increase in LPO concentration and a marked reduction in SOD and CAT enzyme activity were observed in DC rats; there was no significant variation in renal tissue GSH-Px in this group. However, alterations in DC rats were completely restored from 1st month after PT; all evaluated enzyme levels did not significantly differ (P < .01) from those in NC controls.Conclusion. Successful PT controlled cellular oxidative stress in diabetic kidneys, which may prevent chronic lesions.

Folic acid supplementation during early hepatocarcinogenesis: cellular and molecular effects

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

Experimental infection of Leishmania chagasi in immunosuppressed balb/c mice: cellular immune response and parasite burden

The immune response to leishmaniasis can result in a polarization of a subpopulation of T lymphocytes, which leads to a different cell phenotype and results in immune protection or exacerbation of the disease. Leishmanias persist in the body both in asymptomatic infections and after treatment, representing risks in terms of immunosuppression. The objective of this study was to evaluate the effects of infection and immunosuppression by dexamethasone associated with pentoxifylline on animal weight, spleen weight, the parasitic load in the spleen and liver, as well as the production of IFN-gamma and IL-10 in spleen cell culture of Balb/c mice infected with Leishmania chagasi. The infection did not alter animal weight gain, but spleen weight and size increased. The immunosuppression, induced by dexamethasone associated with pentoxifylline, affected animal weight gain and weight and size of the spleen (in infected and not infected animals). The immunosuppression did not significantly alter the course of the parasite burden in the spleen and liver. Dexamethasone and pentoxifylline affected the studied cytokine production, but not influenced on Th1/Th2 response in infected animals.

Time-dependent alterations of soluble and cellular components in human milk

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

CYR61, a cellular proliferation marker in dogs with prostatic disease

The life expectancy of dogs is increasing and is associated with a greater frequency of age-related disease, including that of the prostate gland. A marker of cell proliferation, CYR61, may be detected in a number of conditions in humans, including hyperplasia and neoplasia. The objective of the present study was to investigate the degree of CYR61 expression in a number of different prostate diseases in dogs in order to understand the potential of this marker for diagnosis of prostatic disease. Immunohistochemistry with a CYR61 antibody was performed on prostatic tissue from 22 dogs with different diseases. Intense stromal staining was observed in cases of prostatic dysplasia and benign prostate hyperplasia. In contrast, CYR61 staining was very intense in alveolar epithelial cells in cases of epithelial benign prostate hyperplasia and one case of adenocarcinoma. An obvious CYR61 staining pattern was absent in cases of prostatitis. In conclusion, CYR61 may be a useful marker of cell proliferation in a number of prostatic pathologies, although further studies of normal tissue are warranted. (c) 2006 Elsevier B.V. All rights reserved.

Canine Subcutaneous Mast Cell Tumors: Cellular Proliferation and KIT Expression as Prognostic Indices

Molecular assays are widely used to prognosticate canine cutaneous mast cell tumors (MCT). There is limited information about these prognostic assays used on MCT that arise in the subcutis. The aims of this study were to evaluate the utility of KIT immunohistochemical labeling pattern, c-KIT mutational status (presence of internal tandem duplications in exon 11), and proliferation markers-including mitotic index, Ki67, and argyrophilic nucleolar organizing regions (AgNOR)-as independent prognostic markers for local recurrence and/or metastasis in canine subcutaneous MCT. A case-control design was used to analyze 60 subcutaneous MCT from 60 dogs, consisting of 24 dogs with subsequent local recurrence and 12 dogs with metastasis, as compared to dogs matched by breed, age, and sex with subcutaneous MCT that did not experience these events. Mitotic index, Ki67, the combination of Ki67 and AgNOR, and KIT cellular localization pattern were significantly associated with local recurrence and metastasis, thereby demonstrating their prognostic value for subcutaneous MCT. No internal tandem duplication mutations were detected in exon 11 of c-KIT in any tumors. Because c-KIT mutations have been demonstrated in only 20 to 30% of cutaneous MCT and primarily in tumors of higher grade, the number of subcutaneous MCT analyzed in this study may be insufficient to draw conclusions on the role c-KIT mutations in these tumors.

Towards the prediction of essential genes by integration of network topology, cellular localization and biological process information

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

Nematode burdens and cellular responses in the abomasal mucosa and blood of Florida Native, Rambouillet and crossbreed lambs

This experiment was carried out to compare the worm burden and cellular responses in the abomasal mucosa and blood of Florida Native and Rambouillet lambs and also in animals produced by crosses of these two breeds (generations F1 and F2). Animals were exposed to infection by gastrointestinal nematodes on three different occasions. The first infection was natural, occurring while they were suckling lambs. After weaning, they were kept indoors for 53 days and then were allowed to graze a contaminated pasture for 50 days for a second natural infection. The third infection was an artificial challenge with 6000 Haemonchus contortus infective larvae. The highest mean fecal egg counts (FEC) values were found in Rambouillet lambs followed in decreasing order by F1, F2 and Florida Native lambs. Throughout the trial, most of the high mean packed cell volumes and plasma protein levels were recorded in the F2 lambs; in contrast, most of the low values were found in the Rambouillet lambs. During the natural infection period, the highest percentages of larvae in the fecal cultures of the lambs were Haemonchus. However, high percentages of Trichostrongylus larvae were found particularly in Florida Native lambs. The mean number of blood eosinophils increased after the artificial challenge, reached a peak 21 days after infection and then declined. The highest and lowest blood eosinophil means were recorded in F2 and Florida Native lambs, respectively. The H. contortus burden was significantly higher in Rambouillet and in F1 lambs than in Florida Native and F2 lambs (p < 0.05), while no significant differences were recorded among eosinophil, mast cell and globule leucocyte counts in the abomasal mucosa (p > 0.05). The highest correlation coefficient recorded at the end of this study was between FEC and worm burden (r = 0.7). These two parameters showed a moderate negative correlation with PCV, plasma protein and mast cell counts in the abomasal mucosa. The results obtained in this study indicate that crossbreeding Florida Native and Rambouillet sheep can be a rapid way to combine and improve the characteristics of these two breeds. The parasitological results were promising. however, more studies will be necessary to verify the impact of crossbreeding in other traits. (C) 1999 Elsevier B.V. B.V. All rights reserved.

Cellular and extracellular behavior in the gerbil (Meriones unguiculatus) ventral prostate following different types of castration and the consequences of testosterone replacement

Mongolian gerbils (Meriones unguiculatus) were grouped into two experimental groups: GEx.01 suffered orchiectomy and after 30 days received doses of testosterone cipionate (T), while GEx.02 received weekly and alternated doses of the anti-androgens cyproterone acetate and flutamide for 30 days, and the animals were then euthanized. Structural evaluation reveals a more intense reduction in epithelial height in GEx.02. Smooth muscle cells (SMC) presented a star-shaped aspect after 30 days of hormonal ablation and basal membrane was shown to be more intensely grooved in GEx.01. In both groups, after hormonal replacement, recovery in epithelial height could be noted and the SMC presented its phenotypes, but an increase in RER was seen, characterizing a modulation from its contractile to secreting phenotype. In conclusion, the prostate presented involution capacity after androgen ablation and the ability to reorganize after hormonal replacement, but events resulting from orchiectomy and subsequent T replacement were shown to be more aggressive to the prostate. (c) 2006 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.