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Biomedical subjects

A A Teixeira

Publications and source records attributed to A A Teixeira.

12 recordsLinked to original sources
PubMed2006

Anaerobic digestion of space mission wastes.

The technical feasibility of applying leachbed high-solids anaerobic digestion for reduction and stabilization of the organic fraction of solid wastes generated during space missions was investigated. This process has the advantages of not requiring oxygen or high temperature and pressure while producing methane, carbon dioxide, nutrients, and compost as valuable products. Anaerobic biochemical methane potential assays run on several waste feedstocks expected during space missions resulted in ultimate methane yields ranging from 0.23 to 0.30 L g-1 VS added. Modifications for operation of a leachbed anaerobic digestion process in space environments were incorporated into a new design, which included; (1) flooded operation to force leachate through densified feedstock beds; and (2) separation of biogas from leachate in a gas collection reservoir. This mode of operation resulted in stable performance with 85% conversion of a typical space solid waste blend, and a methane yield of 0.3 Lg per g VS added after a retention time of 15 days. These results were reproduced in a full-scale prototype system. A detailed analysis of this process was conducted to design the system sized for a space mission with a six-person crew. Anaerobic digestion compared favorably with other technologies for solid waste stabilization.

Anaerobiosis↗
PubMed2003

The source of ochratoxin A in Brazilian coffee and its formation in relation to processing methods.

A total of 408 Brazilian coffee samples was examined during the 1999 and 2000 coffee harvest seasons for the presence of ochratoxin A (OA) and fungi with the potential to produce it. Samples came from four regions: Alta Paulista (western area of São Paulo State), Sorocabana (southwest São Paulo State), Alta Mogiana (northeast São Paulo State) and Cerrado Mineiro (western area of Minas Gerais State). Cherries and beans were examined at different stages: immature, mature and overripe cherries from trees, overripe cherries from the ground and beans during drying and storage on the farm. For mycological studies, the cherries and beans were surface disinfected with chlorine, plated on Dichloran 18% Glycerol Agar at 25 degrees C for 5-7 days and analysed for the presence of Aspergillus ochraceus and closely related species, A. carbonarius and A. niger. More than 800 isolates of fungi belonging to these species were identified and studied for the ability to produce OA using the agar plug technique and thin layer chromatography (TLC). A. niger was the species found most commonly (63% of isolates of these three species), but only 3% of them produced OA. A. ochraceus also occurred commonly (31% of isolates), and 75% of those studied were capable of OA production, a much higher percentage than reported elsewhere. A. carbonarius was found (6% of isolates) only in Alta Paulista, the hottest region studied, and only from beans in the drying yard or in storage. However, 77% of the A. carbonarius isolates were capable of producing OA. Average infection rates for cherries taken from trees were very low, but were higher in fruit taken from the ground, from the drying yard and from storage, indicating infection by toxigenic species after harvest. The average OA content in 135 samples of mature cherries from trees, overripe from trees, overripe from the ground, drying yard and storage was 0.1, <0.2, 1.6, 2.1 and 3.3 microg/kg, respectively. Although individual OA levels varied widely, only 9 of the 135 samples analysed exceeded 5 microg/kg OA, with one sample of poor quality dried coffee in excess of 100 microg/kg OA. The causes of high contamination were investigated on the farms concerned and several critical points were found, relating both to local climatic conditions and the drying processes used.

Aspergillus↗
PubMed2001

The West Nile virus encephalitis outbreak in the United States (1999-2000): from Flushing, New York, to beyond its borders.

Viruses cause most forms of encephalitis. The two main types responsible for epidemic encephalitis are enteroviruses and arboviruses. The City of New York reports about 10 cases of encephalitis yearly. Establishing a diagnosis is often difficult. In August 1999, a cluster of five patients with fever, confusion, and weakness were admitted to a community hospital in Flushing, New York. Flaccid paralysis developed in four of the five patients, and they required ventilatory support. Three, less severe, cases presented later in the same month. An investigation was conducted by the NewYork City (NYC) and New York State (NYS) health departments and the national Centers for Disease Control and Prevention (CDC). The West Nile virus (WNV) was identified as the etiologic agent. WNV is an arthropod-borne flavivirus, with a geographic distribution in Africa, the Middle East, and southwestern Asia. It has also been isolated in Australia and sporadically in Europe but never in the Americas. The majority of people infected have no symptoms. Fever, severe myalgias, headache, conjunctivitis, lymphadenopathy, and a roseolar rash can occur. Rarely, encephalitis or meningitis is seen. The NYC outbreak resulted in the first cases of WNV infection in the Western Hemisphere and the first arboviral infection in NYC since yellow fever in the nineteenth century. The WNV is now a public health concern in the United States.

Disease Outbreaks↗
PubMed2000

The West Nile Virus outbreak of 1999 in New York: the Flushing Hospital experience.

West Nile Virus (WNV) is a mosquito-borne flavivirus, which has been known to cause human infection in Africa, the Middle East, and southwestern Asia. It has also been isolated in Australia and sporadically in Europe but never in the Americas. Clinical features include acute fever, severe myalgias, headache, conjunctivitis, lymphadenopathy, and a roseolar rash. Rarely is encephalitis or meningitis seen. During the month of August 1999, a cluster of 5 patients with fever, confusion, and weakness were admitted to the intensive care unit of the same hospital in New York City. Ultimately 4 of the 5 developed flaccid paralysis and required ventilatory support. Three patients with less-severe cases presented shortly thereafter. With the assistance of the New York City and New York State health departments and the Centers for Disease Control and Prevention, these were documented as the first cases of WNV infection on this continent.

Adult↗
PubMed2000

Comparison of capillary and test tube procedures for analysis of thermal inactivation kinetics of mold spores.

Characteristics of capillary and test tube procedures for thermal inactivation kinetic analysis of microbial cells were studied for mold spores. During heating, capillaries were submerged in a water bath and test tubes were held with their caps positioned above the level of the heating medium. Thermal inactivation curves of Aspergillus niger spores in capillaries at around 60 degrees C consisted of a shoulder and a fast linear decline, whereas curves in test tubes consisted of a shoulder, a fast linear decline, and a horizontal tail. There were no significant differences in values of the rate and the delay of fast declines in curves between the procedures. Some experiments were done to clarify the cause for tailing with test tubes. There were no tails with test tubes whose inner walls were not contaminated by A. niger spores, suggesting that tails arise from A. niger spores contaminating the inner walls of test tubes. Temperature of the inner wall at the level of a heating medium was lower than that of the medium. Further, there were no tails for test tubes submerged in the heating medium. These results showed that the reason for survival of contaminants on the upper wall of test tubes was that cells were not subjected to sufficient inactivation temperature. Finally, thermal inactivation curves of A. niger spores in capillaries at various constant temperatures were studied. Curves consisted of a shoulder and a fast linear decline at 57 degrees C and above, whereas curves at below 57 degrees C consisted of a shoulder, a fast linear decline, and a sloping tail.

Aspergillus niger↗
PubMed1990

Hepatic abscess in Crohn's disease.

Hepatic abscess is a rare complication of Crohn's disease. The present report describes an additional case diagnosed by CT scanning and successfully treated by surgery. Recognition of this complication is important because early therapy could improve the prognosis.

Adult↗
PubMed1987

Effects of denervation induced by 6-hydroxydopamine on cell nucleus activity of arterial and cardiac cells of the dog.

1 Denervation was induced in dogs by 6-hydroxydopamine (6-OHDA) treatment. The effects of this on cell nucleus activity of smooth muscle cells and fibroblasts of the mesenteric artery (main trunk and jejunal branches) and of myocardial cells, fibroblasts and endothelial capillary cells of the heart were studied. 2 Changes in the nucleii or cell size measured with light microscopy morphometric techniques and frequency of nucleoli in myocardial cells were chosen as indices of cell nucleus activity state. 3 Noradrenaline depletion 5 days after initiation of 6-OHDA administration was much more marked in the heart (with a content of 10% of control values) than in the arterial vessels (with a content of 50% of control values). 4 Denervation by 6-OHDA led to an increase in the synthetic activity state of the cell nucleus in all cell types and tissues. 5 Plasma noradrenaline and adrenaline levels were strikingly increased by 6-OHDA treatment. 6 The results strongly support the hypothesis of a nuclear modulating effect of the sympathetic innervation upon the effector cells. The incapacity of high noradrenaline plasma levels to prevent the consequences of sympathetic denervation on the effector cells appears to indicate that in the sympathetic innervation there is a 'trophic factor' which is not identical with noradrenaline.

Animals↗
PubMed1984

Structural and functional alterations caused at the extraneuronal level by sympathetic denervation of blood vessels.

The lateral saphenous vein of the dog and the rabbit ear artery were surgically denervated, by clamping the vessel or by removal of the superior cervical ganglion, respectively. Both procedures resulted in denervation of the vessels. The denervated, lateral saphenous vein was supersensitive to exogenous noradrenaline and inactivation of the amine (in oil immersion experiments) was slower in denervated vein strips than in control strips treated with cocaine. Incubation experiments with 3H-noradrenaline confirmed that denervated strips formed considerably fewer metabolites than control ones (in the absence or presence of cocaine) and that O-methylation of noradrenaline was reduced by about 50%. When the strips were incubated with 3H-isoprenaline, the denervated ones accumulated and metabolized isoprenaline to a lesser degree than control strips. Hydrocortisone did not reduce the accumulation of isoprenaline in the denervated vein and had only minor effects on O-methylation. The metabolism of noradrenaline and isoprenaline gradually recovered with time. In the ear artery, denervation was accompanied by a marked reduction in O-methylation, but not in accumulation, of isoprenaline. In both vessels there was a highly significant positive correlation between noradrenaline content and O-methylating capacity; in the saphenous vein accumulation of isoprenaline was also positively correlated to noradrenaline content. Morphological changes observed in the denervated vessels consisted essentially in dedifferentiation of smooth muscle cells (which attained larger dimensions, had an indented, large nucleus, augmented euchromatin and an increased amount of ribosomes), abundance of extracellular material and fibroblasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Kinetic parameters estimation for ascorbic acid degradation in fruit nectar using the Partial Equivalent Isothermal Exposures (PEIE) method under non-isothermal continuous heating conditions.

With the purpose of testing the Paired Equivalent Isothermal Exposures (PEIE) method to determine reaction kinetic parameters under non-isothermal conditions, continuous pasteurizations were carried out with a tropical fruit nectar [25% cupuaçu (Theobroma grandiflorum) pulp and 15% sugar] to estimate the ascorbic acid thermal degradation kinetic parameters. Fifteen continuous thermal exposures were studied, with seven being cycled. The experimental ascorbic acid thermal degradation kinetic parameters were estimated by the PEIE method (E(a) = 73 +/- 9 kJ/mol, k(8)(0)( degrees )(C) = 0.017 +/- 0.001 min(-)(1)). These values compared very well to the previously determined values for the same product under isothermal conditions (E(a) = 73 +/- 7 kJ/mol, k(8)(0)( degrees )(C) = 0.020 +/- 0.001 min(-)(1)). The predicted extents of reaction presented a good fit to the experimental data, although the cycled thermal treatments presented some deviation. In addition to being easier and faster than the Isothermal method, the PEIE method can be a more reliable method to estimate first-order reaction kinetic parameters when continuous heating is considered.

Ascorbic Acid↗