Sorption-desorption of selenite and selenate on Mg-Al layered double hydroxide in competition with nitrate, sulfate and phosphate

Selenate and selenite are considered emerging contaminants and pose a risk to living organisms. Since selenium anion species are at low concentration in aquatic environments, materials for its retention are required to enable monitoring. Herein, hydrotalcite was calcined and characterised to investigate sorption and desorption of selenite and selenate in competition with nitrate, sulfate and phosphate. Sorption experiments were carried out in batch system and desorption by sequential dilution. Selenite and selenate concentration remaining after N desorption steps was determined by mass balance. The isotherms were adjusted to the dual-mode Langmuir-Freundlich model (R² > 0.99). Maximum sorption capacity ranged from 494 to 563 meq kg^-1 for selenite and from 609 to 659 meq kg^-1 for selenate. Sulfate and phosphate ions showed greater competitive effect on the sorption of selenate and selenite, respectively. Low mobilization factors and high sorption efficiency (MF<3%; SE ≈ 100%) indicated that calcined hydrotalcite has the wanted characteristics for retention of relevant selenium anion species in aqueous media.

Sorption and desorption of silver ions by bentonite clays

Anthropogenic activities have increased the concentration of metal species in the environment. The toxicity of silver ions to aquatic and terrestrial organisms has required monitoring by analytical methods, besides actions to promote its control as pollutant. Sorption and desorption processes are directly related to the mobility and availability of metal ions in the environment. In this context, clay minerals can be used for pre-concentration, removal and recovery of silver ions from aqueous solution. Herein, two bentonite clays (BaVC-1 and SWy-2) were characterised and applied to investigate the sorption and desorption of silver ions. Isotherms were fitted to the dual-mode Langmuir-Freundlich model to qualify and quantify sorption sites and evaluate the mobilisation process. The maximum sorption capacity was 743 and 849 meq kg^-1 for BaVC-1 and SWy-2, respectively. Hysteresis index (HI) and mobilisation factor (MF) suggest that the desorption of silver ions in BaVC-1 is about four times more conducive compared to that in SWy-2, although both materials have demonstrated a great potential for Ag⁺ pre-concentration from aqueous solutions.

Differentiation of the bovine dominant follicle from the cohort upregulates mRNA expression for new tissue development genes

This study was designed to identify genes that regulate the transition from FSH- to LH-dependent development in the bovine dominant follicle (DF). Serial analysis of gene expression (SAGE) was used to compare the transcriptome of granulosa cells isolated from the most oestrogenic growing cohort follicle (COH), the newly selected DF and its largest subordinate follicle (SF) which is destined for atresia. Follicle diameter, follicular fluid oestradiol (E) and E:progesterone ratio confirmed follicle identity. Results show that there are 93 transcript species differentially expressed in DF granulosa cells, but only 8 of these encode proteins known to be involved in DF development. Most characterised transcripts upregulated in the DF are from tissue development genes that regulate cell differentiation, proliferation, apoptosis, signalling and tissue remodelling. Semiquantitative real-time PCR analysis confirmed seven genes with upregulated (P≤0.05) mRNA expression in DF compared with both COH and SF granulosa cells. Thus, the new genes identified by SAGE and real-time PCR, which show enhanced mRNA expression in the DF, may regulate proliferation (cyclin D2;CCND2), prevention of apoptosis or DNA damage (growth arrest and DNA damage-inducible, β;GADD45B), RNA synthesis (splicing factor, arginine/serine rich 9;SFRS9) and unknown processes associated with enhanced steroidogenesis (ovary-specific acidic protein; DQ004742) in granulosa cells of DF at the onset of LH-dependent development. Further studies are required to show whether the expression of identified genes is dysregulated when abnormalities occur during DF selection or subsequent development.

Novel fluorescent probe for low density lipoprotein, based on the enhancement of Europium emission band

We report here the observation of the enhancement of Europium-tetracycline complex emission in Low Density Lipoprotein (LDL) solutions. Europium emission band of tetracycline solution containing Europium (III) chloride hexahydrate was tested to obtain effective enhancement in the presence of native LDL and oxidized LDL. Europium emission lifetime in the presence of lipoproteins was measured, resulting in a simple method to measure the lipoproteins quantity in an aqueous solution at physiological pH. This method shows that the complex can be used as a sensor to determine the different states of native and oxidized LDL in biological fluids.

Geocomputation techniques for spatial analysis: are they relevant to health data?

Geocomputation is an emerging field of research that advocates the use of computationally intensive techniques such as neural networks, heuristic search, and cellular automata for spatial data analysis. Since increasing amounts of health-related data are collected within a geographical frame of reference, geocomputational methods show increasing potential for health data analysis. This paper presents a brief survey of the geocomputational field, including some typical applications and references for further reading.

Evaluation and optimisation of a target-controlled infusion system for administering propofol to dogs as part of a total intravenous anaesthetic technique during dental surgery

The performance of a modified target-controlled infusion system was investigated in 16 dogs undergoing routine dental work, by comparing the predicted concentrations of propofol in venous blood samples with direct measurements; the optimum targets for the induction and maintenance of anaesthesia were also identified. The performance of a target-controlled infusion system is considered clinically acceptable when the median prediction error, a measure of bias, is not greater than +/-10 to 20 per cent, and the median absolute performance error, a measure of the accuracy, is not greater than 20 to 30 per cent. The results fell within these limits indicating that the system performed adequately. The optimal induction target was 3 microg/ml, and anaesthesia of adequate depth and satisfactory quality was achieved with maintenance targets of between 2.5 and 4.7 microg/ml propofol. The system was easy to use and the quality of anaesthesia was adequate for dental work.

[Children with acute respiratory distress syndrome: anatomoclinical and radiologic correlation]

This retrospective study reviews cases of ARDS (Adult Respiratory Distress Syndrome) treated and followed up from October 1988 to December 1990 in the Pediatric Intensive Care Unit of Instituto Fernandes Figueira/FIOCRUZ, Brazil. Clinical, radiological and histopathological features were analyzed and correlated with well defined stages of the disease process. Out of 459 cases, 49 (11%) were selected for further study. In 11 cases, histopathological examination (4 biopsies and 8 autopsies) was performed and then classified into one of the following phases: exsudative, cellular proliferative and late fibrotic. The work emphasizes the need for further clinical and experimental studies in order to define the mechanisms and the impact of this Syndrome in the pediatric population.

Pharmaceutical quality of anthelmintics sold in Kenya

Nine anthelmintic products in pharmacies and from agricultural merchants in Kenya were tested for pharmaceutical quality. The concentration of active drug was compared with the claim on the label, and the variability of several products was tested between batches and between bottles within the same batch. All the products purchased claimed to contain levamisole but its mean (sd) concentration varied from 0 to 118.0 (13.3) per cent of the claimed. The concentration of levamisole in different batches of the same product ranged from 0 to 85.4 per cent of that claimed. One product consisting in part of mebendazole was found to contain 73.2 (9.4) per cent of the claimed concentration of this active component and two products consisting in part of oxyclozanide were found to contain 106.0 (14.4) and 120.6 (6.1) per cent of the expected concentration of oxyclozanide.

A pharmacodynamic study of propofol or propofol and ketamine infusions in ponies undergoing surgery

The pharmacodynamics of infusions of propofol alone (group 1) were compared with the pharmacodynamics of infusions of propofol and ketamine together (group 2) in eight ponies undergoing castration. Anaesthesia was induced with detomidine, 20 micrograms kg-1, followed by ketamine, 2.2 mg kg-1. Subsequently, a bolus dose of propofol, 0.5 mg kg-1, was administered intravenously to both groups, and an infusion of propofol was given for an average of 74 minutes to group 1, and an infusion of propofol and ketamine was given for 60 minutes to group 2. The mean (SD) infusion rates of propofol were 0.330 (0.050) mg kg-1 min-1 in group 1, and 0.124 (0.009) mg kg-1 in group 2, and the ketamine infusion rate was maintained constant at 40 micrograms kg-1 min-1. Arterial hypotension and marked respiratory depression were evident in some of the ponies receiving propofol alone, whereas in the ponies anaesthetised with propofol and ketamine, respiratory and cardiovascular parameters were well maintained. All the ponies in both groups recovered quickly from anaesthesia, with mean times to sternal recumbency and standing of 19.8 (8.0) minutes and 27.2 (7.4) minutes respectively for group 1 and 8.4 (3.2) min and 14.9 (10.1) minutes for group 2.

Simultaneous infusions of propofol and ketamine in ponies premedicated with detomidine: a pharmacokinetic study

The pharmacokinetics of propofol and ketamine administered together by infusion were investigated in four ponies. Blood propofol and plasma ketamine and norketamine concentrations were measured by high performance liquid chromatography. After premedication with detomidine (20 micrograms kg-1) anaesthesia was induced with ketamine (2.2 mg kg-1 intravenously). The trachea was intubated and the ponies were allowed to breathe 100 per cent oxygen. A bolus dose of propofol (0.5 mg kg-1) was then administered intravenously and propofol and ketamine were infused for 60 and 45 minutes, respectively. The average mean infusion rate of propofol was 0.136 mg kg-1 min-1, and the ketamine infusion rate was maintained at 50 micrograms kg-1 min-1. The mean (SD) elimination half-lives of propofol and ketamine were 69.0 (8.0) and 89.8 (26.7) minutes, the mean volumes of distribution at steady state were 0.894 (0.161) litre kg-1 and 1.432 (0.324) litre kg-1; the mean body clearances were 33.1 (4.5) and 23.9 (3.8) ml kg-1 min-1 and the mean residence times for the infusion were 87.1 (4.1) and 110.7 (8.2) minutes, respectively. Norketamine, the main metabolite of ketamine, was detected throughout the sampling period. The mean residence time for norketamine was 144 (16) minutes. All the ponies recovered quickly from the anaesthesia; the mean times to sternal recumbency and standing were 11.1 (5.3) and 30.0 (20.8) minutes, respectively, from the end of the infusion.

Analysis of Indole-3-Acetic Acid Metabolites from Dalbergia dolichopetala by High Performance Liquid Chromatography-Mass Spectrometry

A mixture of [2-(14)C(1)] and [(13)C(6)]indole-3-acetic acid was applied to the cotyledons of 6-day-germinated seeds of "jacarandá do cerrado" (Dalbergia dolichopetala) and after 8 hours the seeds were extracted. Analysis of the fractionated extract by reversed-phase high performance liquid chromatography-radiocounting revealed the presence of five radiolabeled metabolite peaks (I-V). After further purification, the individual peaks of radioactivity were analyzed by combined high performance liquid chromatography-steel filter-fast atom bombardment-mass spectrometry. The metabolite fraction V was found to contain [(14)C(1), (13)C(6)]indole-3-acetylas-partic acid and unlabeled indole-3-acetylglutamic acid. Analysis of the metabolite fraction II revealed the presence of dioxindole-3-acetylaspartic acid and putative dioxindole-3-acetylglutamic acid as well as putative benzene ring-hydroxylated derivatives of oxindole-3-acetylaspartic acid and oxindole-3-acetylglutamic acid. There was no evidence of significant incorporation of label from [2'-(14)C(1)] or [(13)C(6)]indole-3-acetic acid into any of these conjugated indoles.

Fatty acid composition of amastigote and trypomastigote forms of Trypanosoma cruzi

The fatty acid composition of total lipids from trypomastigote and amastigote forms of Trypanosoma cruzi and of Vero cells before and after parasite infection were analyzed by gas-liquid chromatography and mass spectrometry. Even-numbered, saturated, monoenoic and polyenoic acids ranging from C-12 to C-18 were characterized in both T. cruzi development stages. Significant changes in the fatty acid composition occurred during the T. cruzi life cycle. Oleic and linoleic acids were prominent in trypomastigote forms, whereas palmitic acid was the major fatty acid of amastigotes. Other differences include higher stearic acid and lower palmitoleic and linolenic acid levels as well as the absence of lauric acid in amastigotes as compared with trypomastigote forms. The fatty acid pattern of Vero cells before T. cruzi infection as compared with that after infection showed mostly qualitative differences. Linoleic and linolenic acids were observed only in T. cruzi infected cells.

The biosynthesis and conjugation of indole-3-acetic acid in germinating seed and seedlings ofDalbergia dolichopetala

Germinating seed ofDalbergia dolichopetala converted both [(2)H5]L-tryptophan and [(2)H5]indole-3-ethanol to [(2)H5]indole-3-acetic acid (IAA). Metabolism of [2'-(14)C]IAA resulted in the production of indole-3-acetylaspartic acid (IAAsp), as well as several unidentified components, referred to as metabolites I, II, IV and V. Re-application of [(14)C]IAAsp to the germinating seed led to the accumulation of the polar, water-soluble compound, metabolite V, as the major metabolite, together with a small amount of IAA. Metabolites I, II and IV were not detected, nor were these compounds associated with the metabolism of [2'-(14)C]IAA by shoots and excised cotyledons and roots from 26-d-oldD. dolichopetala seedlings. Both shoots and cotyledons converted IAA to IAAsp and metabolite V, while IAAsp was the only metabolite detected in extracts from excised roots. The available evidence indicates that inDalbergia, and other species, IAAsp may not act as a storage product that can be hydrolysed to provide the plant with a ready supply of IAA.

Analysis of Indole-3-Acetic Acid and Related Indoles in Culture Medium from Azospirillum lipoferum and Azospirillum brasilense

Analysis of neutral and acidic ethyl acetate extracts from culture medium of Azospirillum brasilense 703Ebc by high-performance liquid chromatography (HPLC) and combined gas chromatography-mass spectrometry demonstrated the presence of indole-3-acetic acid (IAA), indole-3-ethanol, indole-3-methanol, and indole-3-lactic acid. IAA in media of 20 strains of A. brasilense and Azospirillum lipoferum was analyzed quantitatively by both the colorimetric Salkowski assay and HPLC-based isotopic dilution procedures. There was little correlation between the estimates obtained with the two procedures. For instance, the Salkowski assay suggested that the culture medium from A. brasilense 703Ebc contained 26.1 μg of IAA ml −1 , whereas HPLC revealed the presence of only 0.5 μg of IAA ml −1 . Equivalent estimates with A. brasilense 204Ed were 10.5 and 0.01 μg of IAA ml −1 , respectively. The data demonstrate that the Salkowski assay is not a reliable method for measuring the IAA content of Azospirillum culture medium and that estimates in excess of 10 μg of IAA ml −1 should be viewed with particular caution. Metabolism of [2′- 14 C]IAA by A. brasilense 703Ebc yielded radiolabeled indole-3-methanol, whereas roots of maize ( Zea mays L.) seedlings gave rise to [ 14 C]oxindole-3-acetic acid and an array of polar metabolites. Metabolism of [2′- 14 C]IAA by maize roots inoculated with A. brasilense 703Ebc produced a metabolic profile characteristic of maize rather than Azospirillum species.