Papers by Guilherme Castro
Journal of lipid research, 1994
We used defined, reconstituted high density lipoproteins (rHDL) to study the effects of structure... more We used defined, reconstituted high density lipoproteins (rHDL) to study the effects of structure and composition of these particles on their role as cholesterol acceptors from cell membranes or from low density lipoproteins (LDL). Three discoidal rHDL and one spherical rHDL with distinct apolipoprotein A-I conformations, diameters and compositions were used in conjunction with Ob1771 cells to measure the rate of [3H]cholesterol efflux from the cells, direct binding to the cells, and competition with native HDL3 for binding. In addition, the same rHDL particles were used to study the kinetics of cholesterol mass transfer from LDL. The results show that the rates of cholesterol transfer depend on the nature of the donor (t1/2 11-19 min from LDL, and t1/2 5 h from the cells), on the phosphatidylcholine/cholesterol ratio in the acceptors (the closer this ratio is to the equilibrium value, the slower is the rate), and on the diameter of the acceptors (the smallest particles have the low...
Surface Science, 1994
ABSTRACT The interaction of H2 with the ordered Cu3Pt(111) surface has been studied with Auger el... more ABSTRACT The interaction of H2 with the ordered Cu3Pt(111) surface has been studied with Auger electron spectroscopy (AES), low energy electron diffraction (LEED), thermal desorption spectroscopy (TDS), UV-photoelectron spectroscopy (UPS), and work function measurements (Δφ). The ordered Cu3Pt(111) surface consists of a 2 × 2 lattice of isolated Pt atoms completely surrounded by Cu atoms . In contrast to Cu(111) hydrogen adsorption does take place. TD spectra exhibit only one H2 desorption state of second order desorption kinetics and show no evidence for a compression of the H layer at higher coverages in contrast to Pt(111). The H induced changes in the substrate valence band spectra (UPS) suggest H adsorption at Pt sites. Preadsorption of CO on the Pt atoms blocks the H2 adsorption, and the H coverage depends on the number of CO free Pt atoms. All these results are interpreted in terms of the Pt atoms — although isolated — to provide the channel for H adsorption.
Oral Surgery, Oral Medicine, Oral Pathology, 1993
The aneurysmal bone cyst is an enigmatic and misnamed lesion displaying variable etiopathogenic a... more The aneurysmal bone cyst is an enigmatic and misnamed lesion displaying variable etiopathogenic and histologic characteristics, The aneurysmal bone cyst may appear as a primary lesion or as a secondary lesion associated with other pathologic entities. This article presents a probable self-limiting lesion that provides an opportunity to present an approach to classifying aneurysmal bone lesions.
Comparative Biochemistry and Physiology Part A: Physiology, 1985
Do the physiological capacities for dealing with cold and hypoxia vary among populations of the r... more Do the physiological capacities for dealing with cold and hypoxia vary among populations of the rufous-collared sparrow (Zonorrichia cupensis) living at sea level and 4500 m? 2. Body mass and linear dimensions of montane and lowland individuals did not vary significantly. 3. The lower critical temperature of montane birds is approximately 10°C below that of the lowland birds. Therefore, montane populations have apparently developed enhanced capacities for dealing with cold. 4. Lowland and montane sparrows exhibited similar metabolic responses to hypoxia. Individuals of both groups were able to maintain normal levels of oxygen consumption at 80 torr.
Acta Neurochirurgica Supplements
Science, 1996
Apolipoproteins are protein constituents of plasma lipid transport particles. Human apolipoprotei... more Apolipoproteins are protein constituents of plasma lipid transport particles. Human apolipoprotein A-IV (apoA-IV) was expressed in the liver of C57BL/6 mice and mice deficient in apoE, both of which are prone to atherosclerosis, to investigate whether apoA-IV protects against this disease. In transgenic C57BL/6 mice on an atherogenic diet, the serum concentration of high density lipoprotein (HDL) cholesterol increased by 35 percent, whereas the concentration of endogenous apoA-I decreased by 29 percent, relative to those in transgenic mice on a normal diet. Expression of human apoA-IV in apoE-deficient mice on a normal diet resulted in an even more severe atherogenic lipoprotein profile, without affecting the concentration of HDL cholesterol, than that in nontransgenic apoE-deficient mice. However, transgenic mice of both backgrounds showed a substantial reduction in the size of atherosclerotic lesions. Thus, apoA-IV appears to protect against atherosclerosis by a mechanism that does not involve an increase in HDL cholesterol concentration.
New England Journal of Medicine, 2006
Acidic soils Temperature 12C-30C Mexico to Argentina Most common in southeast Brazil Ab... more Acidic soils Temperature 12C-30C Mexico to Argentina Most common in southeast Brazil About 80% of cases 1-3 cases per 100,000 inhabitants Rare outside endemic areas North America infections may be linked to latent infections (all cases once resided in endemic areas)
International Journal of Environmental Science and Technology, 2013
Arteriosclerosis, Thrombosis, and Vascular Biology, 2004
Objective— Uptake of modified low-density lipoprotein (LDL) by macrophages through scavenger rece... more Objective— Uptake of modified low-density lipoprotein (LDL) by macrophages through scavenger receptors results in lipid droplets accumulation and foam cell formation. Excess lipid deposition in macrophages has been reported to modulate expression of several genes including adipophilin. In this study, we investigated the function of adipophilin in lipid accumulation and cholesterol efflux in THP-1 macrophages. Methods and Results— Adipophilin mRNA expression was 3.5-fold higher in human atherosclerotic plaques compared with healthy areas of the same arteries. Moreover, in the presence of acetylated LDL (AcLDL), triglycerides and cholesteryl esters were increased in macrophages overexpressing adipophilin by 40% and 67%, respectively, whereas their accumulation was reduced when endogenous cellular adipophilin was depleted using siRNA approach. In addition, neither overexpression nor downregulation of adipophilin altered expression of genes involved in lipid efflux. However, the affinit...
Within the next few years the number of shorebird color marking projects in the New World is like... more Within the next few years the number of shorebird color marking projects in the New World is likely to expand considerably. One coFmon goal shared by many of these programs is tracking movements between breeding and wintering grounds, and identifying stopover sites used by specific populations during migration. The prospect for success in this work is enhanced greatly by expanding the number of projects involved. But this expansion may result largely in confusion, unless considerable effort is made to coordinate color-marking schemes. We outline here a system that should function if adopted by shorebird banders working in the New World. The system wepropose is based on a series of practical considerations and research goals, sun•rizedbelow. The system is complex, but so is the problem it addresses. No perfect solution is available given the diversity of interests and countries and the limitations on materials and resources. We hope this system strikes a reasonable balance. We hope that researchers will provide feedback to us on its usefulness and drawbacks.
We color-marked Sanderlings (Calidris alba Pallas) at 19 locations in 6 countries in the New Worl... more We color-marked Sanderlings (Calidris alba Pallas) at 19 locations in 6 countries in the New World and coordinated a network of volunteers to locate banded individuals in migration over a five-year period. The observers reported 252 independent sightings of birds in countries different from the country of banding. Sanderlings that migrate north to the Arctic from Chile and Peru travel principally through the central corridor (Texas and northward) of the United States and Canada; smaller numbers follow the Pacific coast. A few migrate north from the Pacific coast of South America along the Atlantic coast of the United States. Southbound from the Arctic to coastal Chile and Peru, many individuals switch eastward to stopovers on the Atlantic coast, including birds that migrated north along the U.S. Pacific coast. Sanderlings banded in Brazil during the nonbreeding period appear only on the U.S. Atlantic coast in migration. Our results emphasize the individual nature of migration. We found considerable heterogeneity in migratory behavior among individuals that spend the nonbreeding season together on the same beaches. Individuals from widely separated nonbreeding sites often shared similar pathways. In this species and perhaps in others, no simple single migratory route connects breeding with nonbreeding regions.
The gastrointestinal tract is highly sensitive to ionizing radiation. Some of the most radiosensi... more The gastrointestinal tract is highly sensitive to ionizing radiation. Some of the most radiosensitive cells in this system are mast cells and epithelium. This article describes experiments that test the hypothesis that irradiation suppresses mucosal immune responses in which mast cells and epithelium are involved. The hypothesis was tested by examining the impact of ionizing radiation on anaphylactically mediated Cl- secretion in jejunum of rats sensitized by Trichinella spiralis infection and challenged with antigen derived from the parasite. Antigen-induced Cl- secretion was measured electrophysiologically in vitro. Rats were immunized by inoculation with 3 x 10(3) T. spiralis larvae and, 30-50 days later, exposed to total abdominal irradiation from a cobalt-60 gamma source. Doses were 5, 7, and 9 Gy. At 1, 3, 5, 7, 14, and 21 days postirradiation (DPI), jejunal segments were assessed for immune responsiveness. (Duration of suppression to antigenic challenge was directly related to radiation dose). Recovery of response to antigenic challenge after irradiation with 5 Gy was complete by 5 DPI. At 7 Gy, responsiveness was totally suppressed from 1 to 5 DPI, was partially expressed from 5 to 14 DPI, and was completely restored by 21 DPI. A dose of 9 Gy completely suppressed immune responsiveness throughout the 21-day period. Full responsiveness of jejunum to exogenous Cl- secretagogues at 1-5 DPI indicates that the immunosuppressive effect of radiation was not due to a breakdown in the secretory process at the epithelium level.(ABSTRACT TRUNCATED AT 250 WORDS)
American Journal of Medical Genetics Part A, 2007
Niemann-Pick type C1 (NPC1) disease is an autosomal recessive disorder characterized clinically b... more Niemann-Pick type C1 (NPC1) disease is an autosomal recessive disorder characterized clinically by neonatal jaundice, hepatosplenomegaly, vertical gaze palsy, ataxia, dystonia, and progressive neurodegeneration. The present study provides basic clinical and health information from the National Niemann-Pick C1 disease database that was obtained using a clinical questionnaire of 83 questions mailed to families affected by NPC1 disease living in the United States. The study was conducted over a 1-year period, during which time parents/caregivers and physicians completed the clinical questionnaire. Sixty-four percent (87/136) of the questionnaires were returned, with 53% and 47% representing male and female NPC1 patients, respectively. The average age of diagnosis for NPC1 disease was 10.4 years, with one-half of patients being diagnosed before the age of 6.9 years. The average age of death for NPC1 disease was 16.2 years, with one-half of patients dying before the age of 12.5 years. A common clinical symptom reported at birth was neonatal jaundice (52%), followed by enlargement of the spleen (36%) and liver (31%); ascites (19%) and neonatal hypotonia (6%) were much less frequent. With respect to developmental difficulties, the most common findings included clumsiness (87%), learning difficulties (87%), ataxia (83%), dysphagia (80%), and vertical gaze palsy (81%). Together, these findings confirm and extend previous reports investigating the clinical features associated with NPC1 disease.
Molecular Genetics and Metabolism
BioMed Research International, 2015
The precipitation of calcium carbonate and calcium sulphate by isolated bacteria from seawater an... more The precipitation of calcium carbonate and calcium sulphate by isolated bacteria from seawater and real brine obtained in a desalination plant growth in culture media containing seawater and brine as mineral sources has been studied. However, only bioprecipitation was detected when the bacteria were grown in media with added organic matter. Biomineralization process started rapidly, crystal formation taking place in the beginning a few days after inoculation of media; roughly 90% of total cultivated bacteria showed. Six major colonies with carbonate precipitation capacity dominated bacterial community structure cultivated in heterotrophic platable bacteria medium. Taxonomic identification of these six strains through partial 16S rRNA gene sequences showed their affiliation with Gram-positiveBacillusandVirgibacillusgenera. These strains were able to form calcium carbonate minerals, which precipitated as calcite and aragonite crystals and showed bacterial fingerprints or bacteria calc...
Revista da Sociedade Brasileira de Medicina Tropical
Disseminated infection with Cryptococcus neoformans was observed in a newborn infant who presente... more Disseminated infection with Cryptococcus neoformans was observed in a newborn infant who presented fever and respiratory symptoms since the 52 nd day of life. The mother was infected by human immunodeficiency virus and presented pulmonary and meningeal cryptococcal infection. This is a rare case of cryptococcal infection with probable maternal-fetal transmission.
Bioremediation is an important technology for the restoration of oil polluted environments by ind... more Bioremediation is an important technology for the restoration of oil polluted environments by indigenous or selected microorganisms. In general, the rate of biodegradation depends on the number and types of microorganisms, the nature and chemical structure of pollutants to be degraded and the environmental conditions. In this study we have evaluated the efficacy of the application of four different biostimulation treatments for the biodegradation of diesel contaminated soils. The treatments applied involved: (a) the addition of NPK fertilizer + Ivey I surfactant; (b) the addition of NPK fertilizer + Ethanol; (c) the addition of NPK fertilizer + Biorem; and (d) oxidation by Fenton's reagent combined with NPK fertilizer. Microbial activity was evaluated following growth of heterotrophic and degrading microorganisms, dehydrogenase activity and CO 2 production. Hydrocarbons degradation was established by determination of TPH, alkanes, branched alkanes, pristane and phytane by GC/MS. Our results have shown that the application of NPK fertilizer in combination with Ivey surfactant is an efficient treatment to be applied in clay soil. Treatment with Fenton's reagent previous to the application of NPK fertilizer also efficiently enhanced hydrocarbon biodegradation in saturated conditions.
Genome announcements, 2014
Transplantation Proceedings, 2008
Ascites is a rare complication of renal transplantation. Ascites has been reported after kidney t... more Ascites is a rare complication of renal transplantation. Ascites has been reported after kidney transplantation due to rejection, decapsulation of the graft, urinary or vascular leak, lymphocele, transudation, or infection. While technical complications of the procedure are the most frequent cause, portal hypertension and graft rejection are other causes. Ascites can occur after renal transplantation independent of kidney function. Usually, a time relation can be made between the surgical procedure and ascites development. Chylous ascites is still more uncommon; it is usually related to traumatic lymphatic injury. Drugs are rarely associated with the genesis of ascites. Sirolimus has been associated with a high rate of lymphoceles, lymphedema, and pulmonary alveolar proteinosis. The exact mechanisms remain unknown. The risk for lymphocele formation with sirolimus is 12% to 15%. Ascites is an adverse effect with an incidence between 3% and 20%, but no relation between sirolimus and chylous ascites was previously established. We present a clinical report of chylous ascites in a renal transplant patient under sirolimus therapy; our investigation pointed to sirolimus as the cause.
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Papers by Guilherme Castro