Study of chemical properties and evaluation of collagen in mantle, epidermal connective tissue and tentacle of Indian Squid, Loligo duvauceli Orbigny

The chemical composition and evaluation of Indian squid (Loligo duvauceli) mantle, epidermal connective tissue and tentacle is investigated in this current study. It is observed that squid mantle contains 22.2% total protein; 63.5% of the total protein is myofibrillar protein. The unique property of squid myofibrillar protein is its water solubility. Squid mantle contains 12.0% total collagen. Epidermal connective tissue has highest amounts of total collagen (17.8%). SDS-PAGE of total collagen identified high molecular weight α-, β- and γ- sub-chains. Amino acid profile analysis indicates that mantle and tentacle contain essential amino acids. Arginine forms a major portion of mantle collagen (272.5 g/100 g N). Isoleucine, glutamic acid and lysine are other amino acids that are found in significantly high amounts in the mantle. Sulphur containing cystine is deficit in mantle collagen. Papain digest of mantle and epidermal connective tissue is rich in uronic acid, while papain digest, collagenase digest and urea digest of epidermal connective tissue has significant amounts of sialic acid (25.2, 33.2 and 99.8 μmol /100 g, respectively). PAS staining of papain digest, collagenase digest and urea digest also identify the association of hexoses with low molecular weight collagen fragments. Histochemical sectioning also emphasized the localized distribution of collagen in epidermal and dermal region and very sparse fibres traverse the myotome bundles

β-glucosidases from Aspergillus unguis NII 08123: Molecular characterization, properties and applications

Lignocellulosic biomass is probably the best alternative resource for biofuel production and it is composed mainly of cellulose, hemicelluloses and lignin. Cellulose is the most abundant among the three and conversion of cellulose to glucose is catalyzed by the enzyme cellulase. Cellulases are groups of enzymes act synergistically upon cellulose to produce glucose and comprise of endoglucanase, cellobiohydrolase and β-glucosidase. β -glucosidase assumes great importance due to the fact that it is the rate limiting enzyme. Endoglucanases (EG) produces nicks in the cellulose polymer exposing reducing and non reducing ends, cellobiohydrolases (CBH) acts upon the reducing or non reducing ends to liberate cellobiose units, and β - glucosidases (BGL) cleaves the cellobiose to liberate glucose completing the hydrolysis. . β -glucosidases undergo feedback inhibition by their own product- β glucose, and cellobiose which is their substrate. Few filamentous fungi produce glucose tolerant β - glucosidases which can overcome this inhibition by tolerating the product concentration to a particular threshold. The present study had targeted a filamentous fungus producing glucose tolerant β - glucosidase which was identified by morphological as well as molecular method. The fungus showed 99% similarity to Aspergillus unguis strain which comes under the Aspergillus nidulans group where most of the glucose tolerant β -glucosidase belongs. The culture was designated the strain number NII 08123 and was deposited in the NII culture collection at CSIR-NIIST. β -glucosidase multiplicity is a common occurrence in fungal world and in A.unguis this was demonstrated using zymogram analysis. A total 5 extracellular isoforms were detected in fungus and the expression levels of these five isoforms varied based on the carbon source available in the medium. Three of these 5 isoforms were expressed in higher levels as identified by the increased fluorescence (due to larger amounts of MUG breakdown by enzyme action) and was speculated to contribute significantly to the total _- β glucosidase activity. These isoforms were named as BGL 1, BGL3 and BGL 5. Among the three, BGL5 was demonstrated to be the glucose tolerant β -glucosidase and this was a low molecular weight protein. Major fraction was a high molecular weight protein but with lesser tolerance to glucose. BGL 3 was between the two in both activity and glucose tolerance.121 Glucose tolerant .β -glucosidase was purified and characterized and kinetic analysis showed that the glucose inhibition constant (Ki) of the protein is 800mM and Km and Vmax of the enzyme was found to be 4.854 mM and 2.946 mol min-1mg protein-1respectively. The optimumtemperature was 60°C and pH 6.0. The molecular weight of the purified protein was ~10kDa in both SDS as well as Native PAGE indicating that the glucose tolerant BGL is a monomeric protein.The major β -glucosidase, BGL1 had a pH and temperature optima of 5.0 and 60 °C respectively. The apparent molecular weight of the Native protein is 240kDa. The Vmax and Km was 78.8 mol min-1mg protein-1 and 0.326mM respectively. Degenerate primers were designed for glycosyl hydrolase families 1, 3 and 5 and the BGL genes were amplified from genomic DNA of Aspergillus unguis. The sequence analyses performed on the amplicons results confirmed the presence of all the three genes. Amplicon with a size of ~500bp was sequenced and which matched to a GH1 –BGL from Aspergillus oryzae. GH3 degenerate primers producing amplicons were sequenced and the sequences matched to β - glucosidase of GH3 family from Aspergillus nidulans and Aspergillus acculateus. GH5 degenerate primers also gave amplification and sequencing results indicated the presence of GH5 family BGL gene in the Aspergillus unguis genomic DNA.From the partial gene sequencing results, specific as well as degenerate primers were designed for TAIL PCR. Sequencing results of the 1.0 Kb amplicon matched Aspergillus nidulans β -glucosidase gene which belongs to the GH1 family. The sequence mainly covered the N-Terminal region of the matching peptide. All the three BGL proteins ie. BGL1, BGL3 and BGL5 were purified by chromatography an electro elution from Native PAGE gels and were subjected to MALDI-TOF mass spectrometric analysis. The results showed that BGL1 peptide mass matched to . β -glucosidase-I of Aspergillus flavus which is a 92kDa protein with 69% protein coverage. The glucose tolerant β -glucosidase BGL5 mass matched to the catalytic C-terminal domain of β -glucosidase-F from Emericella nidulans, but the protein coverage was very low compared to the size of the Emericella nidulans protein. While comparing the size of BGL5 from Aspergillus unguis, the protein sequence coverage is more than 80%. BGL F is a glycosyl hydrolase family 3 protein.The properties of BGL5 seem to be very unique, in that it is a GH3 β -glucosidase with a very low molecular weight of ~10kDa and at the same time having catalytic activity and glucose 122 tolerance which is as yet un-described in GH β -glucosidases. The occurrence of a fully functional 10kDA protein with glucose tolerant BGL activity has tremendous implications both from the points of understanding the structure function relationships as well as for applications of BGL enzymes. BGL-3 showed similarity to BGL1 of Aspergillus aculateus which was another GH3 β -glucosidase. It may be noted that though PCR could detect GH1, GH3 and GH5 β-glucosidases in the fungus, the major isoforms BGL1 BGL3 and BGL5 were all GH3 family enzymes. This would imply that β-glucosidases belonging to other families may also co-exist in the fungus and the other minor isoforms detected in zymograms may account for them. In biomass hydrolysis, GT-BGL containing BGL enzyme was supplemented to cellulase and the performances of blends were compared with a cocktail where commercial β- glucosidase was supplemented to the biomass hydrolyzing enzyme preparation. The cocktail supplemented with A unguis BGL preparation yielded 555mg/g sugar in 12h compared to the commercial enzyme preparation which gave only 333mg/g in the same period and the maximum sugar yield of 858 mg/g was attained in 36h by the cocktail containing A. unguis BGL. While the commercial enzyme achieved almost similar sugar yield in 24h, there was rapid drop in sugar concentration after that, indicating probably the conversion of glucose back to di-or oligosaccharides by the transglycosylation activity of the BGl in that preparation. Compared this, the A.unguis enzyme containing preparation supported peak yields for longer duration (upto 48h) which is important for biomass conversion to other products since the hydrolysate has to undergo certain unit operations before it goes into the next stage ie – fermentation in any bioprocesses for production of either fuels or chemicals.. Most importantly the Aspergillus unguis BGL preparation yields approximately 1.6 fold increase in the sugar release compared to the commercial BGL within 12h of time interval and 2.25 fold increase in the sugar release compared to the control ie. Cellulase without BGL supplementation. The current study therefore leads to the identification of a potent new isolate producing glucose tolerant β - glucosidase. The organism identified as Aspergillus unguis comes under the Aspergillus nidulans group where most of the GT-BGL producers belong and the detailed studies showed that the glucose tolerant β -glucosidase was a very low molecular weight protein which probably belongs to the glycosyl hydrolase family 3. Inhibition kinetic studies helped to understand the Ki and it is the second highest among the nidulans group of Aspergilli. This has promoted us for a detailed study regarding the mechanism of glucose tolerance. The proteomic 123 analyses clearly indicate the presence of GH3 catalytic domain in the protein. Since the size of the protein is very low and still its active and showed glucose tolerance it is speculated that this could be an entirely new protein or the modification of the existing β -glucosidase with only the catalytic domain present in it. Hydrolysis experiments also qualify this BGL, a suitable candidate for the enzyme cocktail development for biomass hydrolysis

Factores de riesgo perinatales para sobrepeso y obesidad en escolares en una población bogotana

Objetivo: Evaluar el impacto de los factores maternos y perinatales: peso previo al embarazo, presencia de hipertensión, diabetes y tabaquismo, peso al nacer y tiempo de lactancia con el desarrollo de sobrepeso y obesidad en los niños de 5 a 10 años en una población bogotana. Materiales y métodos: se realizó un diseño de casos y controles no pareado, incluyendo 528 niños con sus respectivas madres con una relación 1:2, en quienes se identificaron los descritos, y también factores postnatales relevantes: dieta, ejercicio y tiempo de pantalla. Se analizó con un modelo de regresión logística binomial la importancia de cada uno para la patología Resultados:Se encontró una mayor prevalencia de casos en los estratos 1 y 2 comparados con los demás estratos (p= 0,034). También se encontraron diferencias en la prevalencia de sobrepeso y obesidad en las madres de los casos (27%; p =0,01), mayor ingesta calórica en el grupo de los controles (42,9% vs 30,9%; p= 0,04). En el modelo de regresión logística se encontró que los factores que en conjunto mostraron significancia estadística fueron, un peso al nacer mayor de 2500 gr OR 2,31(IC 95%:1,13-4,78 p=0,021), un IMC materno antes de la gestación > de 25 OR 3,42(IC 95%:1,42-8,29 p=0,06), peso al año mayor de 7,5 kg OR 2,77 (IC 95%:1,11-2,78 p=0,028) y una ingesta calórica entre 600 a 1900 calorías/día OR 1.58 (IC 95%:1,06-2,35 p=0,02).Conclusiones: son factores de riesgo para el desarrollo de la obesidad infantil, la progresión hacia un percentil superior en peso, antes el embarazo, nacimiento y primer año de vida.

Factores de riesgo asociados al diagnostico de asfixia perinatal en el Hospital Universitario Mayor Méderi, Bogota, 2010-2011.

Objetivo: Determinar los factores de riesgo de anteparto, intraparto y fetales asociados a asfixia perinatal en los recién nacidos del servicio de neonatología del Hospital Universitario Mayor Méderi de Bogotá, 2010-2011. Materiales y métodos: Estudio de casos y controles pareado por fecha de nacimiento, con una relación 1:5(51:306). Las asociaciones se evaluaron con la prueba de ji-cuadrado de Mantel y Haenszel o Test de Fisher para datos pareados, con OR e intervalo de confianza del 95%, el análisis multivariado con un modelo de regresión logística condicional. Resultados: Los factores de riesgo con asociación significativa fueron: - Ante parto: Antecedentes patológicos maternos (OR=6.00,IC95%:1.55-23.19,p=0.013), primigestación (OR=1.91,IC95%:1.02-3.56,p=0,090), -Intraparto: Abruptio de placenta (OR=25,00,IC95%:2.92-213.99,p=0.001), hemorragia del tercer trimestre (OR=12.50,IC95%:2.43-64.43,p=0.001), Oligohidramnios(OR=6.25,IC95%:1.68-23.28,p=0.001), taquicardia fetal (OR=7.66,IC95%:1.67-35.04,p=0.011), monitoreo fetal intraparto anormal (OR=10.33,IC95%:4.38-24.34,p=0.001), expulsivo prolongado(OR=13.00,IC95%:4.63-36.46,p=0.001), fiebre materna(p<0.001), corioamnionitis(p<0.001), convulsiones maternas(p<0.001), bradicardia fetal (p=<0.001), -Fetales: Género masculino(OR=1.87,IC95%:1.02-3.44,p=0.026), edad gestacional por BALLARD igual ó <36semanas(OR=4.78(IC95%:2.21-10.35,p=0.001), vía del nacimiento instrumentado(OR=18,80,IC95%:3.69-39.55,p=0.001), líquido amniótico hemorrágico o teñido de meconio(OR= 9.00,IC95%:3.01-26.85,p=0.001), circular de cordón(OR=9.00,IC95%:3.59-22.52,p=0.001), peso al nacer igual ó <2500 gramos (OR=8.88,IC95%:3.73-21.15,p=0.001). Los subrayados y el síndrome hipertensivo asociado al embarazo se encontraron significativos en análisis multivariado. Conclusiones: Los factores de riesgo para asfixia perinatal fueron: antecedentes patológicos maternos, primigestación, abruptio de placenta, hemorragia del tercer trimestre, oligohidramnios, monitoreo fetal intraparto anormal, taquicardia y bradicardia fetal, expulsivo prolongado, corioamnionitis, fiebre materna, convulsiones maternas, género masculino, edad gestacional por BALLARD igual ó <36 semanas, vía del nacimiento instrumentado, líquido amniótico hemorrágico o teñido de meconio, circular de cordón, peso al nacer igual ó <2500 gramos.

Conflict-induced poverty: Evidence from Colombia

En Colombia, la pobreza y el conflicto están estrechamente relacionados. Este estudio usa medidas de disuasión del gobierno como instrumentos de varias variables específicas de conflicto para estimar el impacto del conflicto sobre la pobreza en Colombia. Usando datos del censo a nivel municipal para el año 2005, evalúo el efecto sobre la incidencia urbana y rural del recientemente-desarrollado Índice de Pobreza Multidimensional. Los resultados sugieren que el conflicto aumenta significativamente la pobreza rural. Esto es consistente con el hecho que la mayor parte del conflicto en Colombia ocurre en las áreas rurales. También evalúo el efecto rezagado del conflicto en la pobreza para concluir que éste dura por al menos tres años pero que decae en el tiempo. Finalmente, pruebo que mis resultados son robustos a una batería de especificaciones adicionales, incluyendo una versión modificada de mi variable dependiente y el uso de una base alternativa de conflicto.

Violence and growth in colombia : a review of the quantitative literature

This is a critical review of the empirical literature on the relationship between violence and economic growth in Colombia: an interesting case study for social scientists studying violence, conflict, crime and development. We argue that, despite the rapid development of this literature and the increasing use of new techniques, there is still much room for research. After assessing the contribution of the most influential papers on the subject, we suggest directions for future research.

Mercados laborales en entornos de conflictos armados: un análisis empírico para Colombia

Históricamente se ha reconocido que los conflictos internos afectan de manera directa variables a nivel individual como la salud de las personas, los niveles de escolaridad y el desplazamiento forzoso de los afectados. Sin embargo, solo hasta la última década las investigaciones académicas se han inclinado en documentar y cuantificar rigurosamente los efectos colaterales de la violencia sobre las condiciones de vida de los individuos. La presente investigación estudia cómo la exposición al conflicto en Colombia ha afectado las decisiones en términos de mercado laboral de las personas. La estrategia de identificación internaliza los reconocidos problemas de endogeneidad del conflicto con variables de actividad y desarrollo económico y presenta resultados robustos a fenómenos de migración interna y desplazamiento. En términos de participación laboral y desempleo, se encuentran efectos heterogéneos a nivel de género como respuestas a la violencia experimentada. En particular, la probabilidad de participación laboral de las mujeres se incremente como consecuencia de la exposición al conflicto, mientras que la de desempleo disminuye. Para los hombres, los resultados muestran una menor probabilidad de participación, efecto contrario al de las mujeres, y un efecto análogo en términos de desempleo. La investigación no encuentra efectos diferenciales en términos de informalidad laboral.

Bioinspired iron and manganese catalysts for the effective and selective oxidation of alkanes and alkenes

La gran eficiència, selectivitat i les condicions suaus exhibides per les reaccions que tenen lloc al centre actiu de les metal·looxigenases són la font d'inspiració per la present dissertació. Amb l'objectiu de dissenyar catalitzadors d'oxidació eficients hem fet ús de dues estratègies: la primera consisteix en el disseny de complexos amb baix pes molecular inspirats en aspectes estructurals de la primera esfera de coordinació del centre metàl·lic d'enzims de ferro i de manganès. Aquests complexos s'han estudiat com a catalitzadors en l'oxidació selectiva d'alcans i d'alquens fent servir oxidants "verds" com ara l'H2O2. La segona estratègia està basada en l'ús de la química supramolecular per tal de desenvolupar estructures moleculars auto-acoblades amb la forma i les propietats químiques desitjades. Concretament, la construcció de nanocontenidors amb un catalitzador d'oxidació incrustat a la seva estructura ens permetria dur a terme reaccions més selectives, tal com passa en les reaccions catalitzades per enzims.

Enhanced phytoextraction: In search of EDTA alternatives

Enhanced phytoextraction proposes the use of soil amendments to increase the heavy-metal content of above-ground harvestable plant tissues. This study compares the effect of synthetic aminopolycarboxylic acids [ethylenediamine tetraacetatic acid (EDTA), nitriloacetic acid (NTA), and diethylenetriamine pentaacetic acid (DTPA)] with a number of biodegradable, low-molecular weight, organic acids (citric acid, ascorbic acid, oxalic acid, salicylic acid, and NH4 acetate) as potential soil amendments for enhancing phytoextraction of heavy metals (Cu, Zn, Cd, Pb, and Ni) by Zea mays. The treatments in this study were applied at a dose of 2 mmol/kg(-1) 1 d before sowing. To compare possible effects between presow and postgermination treatments, a second smaller experiment was conducted in which EDTA, citric acid, and NH4 acetate were added 10 d after germination as opposed to 1 d before sowing. The soil used in this screening was a moderately contaminated topsoil derived from a dredged sediment disposal site. This site has been in an oxidized state for more than 8 years before being used in this research. The high carbonate, high organic matter, and high clay content characteristic to this type of sediment are thought to suppress heavy-metal phytoavailability. Both EDTA and DTPA resulted in increased levels of heavy metals in the above-ground biomass. However, the observed increases in uptake were not as large as reported in the literature. Neither the NTA nor organic acid treatments had any significant effect on uptake when applied prior to sowing. This was attributed to the rapid mineralization of these substances and the relatively low doses applied. The generally low extraction observed in this experiment restricts the use of phytoextraction as an effective remediation alternative under the current conditions, with regard to amendments used, applied dose (2 mmol/kg(-1) soil), application time (presow), plant species (Zea mays), and sediment (calcareous clayey soil) under study.

Vesicular systems for delivering conventional small organic molecules and larger macromolecules to and through human skin

The history of using vesicular systems for drug delivery to and through skin started nearly three decades ago with a study utilizing phospholipid liposomes to improve skin deposition and reduce systemic effects of triamcinolone acetonide. Subsequently, many researchers evaluated liposomes with respect to skin delivery, with the majority of them recording localized effects and relatively few studies showing transdermal delivery effects. Shortly after this, Transfersomes were developed with claims about their ability to deliver their payload into and through the skin with efficiencies similar to subcutaneous administration. Since these vesicles are ultradeformable, they were thought to penetrate intact skin deep enough to reach the systemic circulation. Their mechanisms of action remain controversial with diverse processes being reported. Parallel to this development, other classes of vesicles were produced with ethanol being included into the vesicles to provide flexibility (as in ethosomes) and vesicles were constructed from surfactants and cholesterol (as in niosomes). Thee ultradeformable vesicles showed variable efficiency in delivering low molecular weight and macromolecular drugs. This article will critically evaluate vesicular systems for dermal and transdermal delivery of drugs considering both their efficacy and potential mechanisms of action.

Selective and highly efficient dye scavenging by a pH-responsive molecular hydrogelator

A structurally simple low molecular weight hydrogelator derived from isophthalic acid forms robust pH-responsive hydrogels capable of highly efficient and selective dye adsorption.

Influence of porcine genotype on the abundance of thyroid hormones and leptin in sow milk and its impact on growth, metabolism and expression of key adipose tissue genes in offspring

Neonatal mortality is greater in commercial porcine genotypes, compared with the ancient Meishan breed that rapidly lay down adipose tissue; this may be related to hormones, such as triiodothyronine (T3) or leptin. Leptin is present in maternal milk; however, the extent to which this supply provides the neonate with leptin is unknown, but may play a role in growth and development. We investigated whether thyroid hormones and leptin concentrations in maternal milk differed between genotypes; and whether this influenced piglet concentrations or expression of genes involved in adipose tissue regulation. Eight Meishan and six commercial sows were entered into the study and milk samples from the day of parturition to day 4 postpartum was taken daily. The median birth weight piglet in each litter had a daily venous blood sample taken and was euthanised on day 4. Gene expressions of IGF-I, IGF-binding protein 3 (IGFBP-3), peroxisome proliferators activated receptor (PPAR) and glucocorticoid receptor (GR) were measured in adipose tissue using real-time PCR. T3 was increased in Meishan milk, but not in piglet plasma. Milk thyroxine was similar between breeds but commercial piglet levels were significantly higher. Leptin was higher in commercial sow milk throughout the study. Milk leptin was strongly correlated to plasma leptin during the first postnatal days and also to organ and body weight in Meishan piglets that also had significantly higher expression of GR, but not IGF-I, IGFBP-3 or PPAR. In conclusion, we have found a significant disparity in the provision of thyroid hormones in Meishan and commercial sow’s milk. These changes are not always translated to plasma concentrations of hormone in the piglet. Leptin appears to have a stronger role in growth and development in the Meishan genotype compared with commercial; along with the increased GR expression, this may also represent a potential mechanism behind the rapid accumulation of adipose tissue in Meishan piglets.

The survival, growth and carcase characteristics of crossbred beef cattle in Tanzania

Sires of seven Bos taurus beef breeds were mated with Bos indicus Boran cows at two sites, one near sea level and the other at about 1000 m altitude, and over three years. Purebred Boran calves provided controls for comparisons between sire breeds for growth to 4 years of age, mortality and carcase characteristics in a range environment where all the animals were kept under a similar management regime. Numerous sire breed x site, sire breed x year of birth and site x year of birth interactions were established. Mortality was high, but there was no significant sire breed effect, although purebred Borans had a higher survival than crossbred calves. There was no significant difference between genotypes in birth weight. Generally, Bos taurus cross steers achieved greater live weight gains and heavier carcase weights at 4 years of age than did purebred Borans. Limousin-cross steers had significantly (p<0.05) less fat in the tenth rib sample joint than any of the other genotypes. A productivity index that combined calf survival and carcase weight indicated that the Chianina crosses were more productive than any other genotype at either site. Purebred Borans were more productive than all the Bos taurus crossbreds with the exception of the Chianina crosses at site 1, but were only superior to the Limousin crosses at site 2, which was at the higher altitude. When lean meat yield was introduced into the productivity index, the Boran purebreds were the least productive at site 2.

A novel self-healing supramolecular polymer system

Utilising supramolecular pi-pi stacking interactions to drive miscibility in two-component polymer blends offers a novel approach to producing materials with unique properties. We report in this paper the preparation of a supramolecular polymer network that exploits this principle. A low molecular weight polydiimide which contains multiple pi-electron-poor receptor sites along its backbone forms homogeneous films with a siloxane polymer that features pi-electron-rich pyrenyl end-groups. Compatibility results from a complexation process that involves chain-folding of the polydiimide to create an optimum binding site for the pi-electron-rich chain ends of the polysiloxane. These complementary pi-electron-rich and -poor receptors exhibit rapid and reversible complexation behaviour in solution, and healable characteristics in the solid state in response to temperature. A mechanism is proposed for this thermoreversible healing behaviour that involves disruption of the intermolecular pi-pi stacking cross-links as the temperature of the supramolecular film is increased. The low T-g siloxane component can then flow and as the temperature of the blend is decreased, pi-pi stacking interactions drive formation of a new network and so lead to good damage-recovery characteristics of the two-component blend.

Catalytic oxidation of alcohols using molecular oxygen mediated by poly(ethylene glycol)-supported nitroxyl radicals

The selective catalytic oxidation of alcohols over a mixture of copper(l) chloride and a number of linear 'linker-less' or 'branched' poly(ethylene glycol)-supported nitroxyl radicals of the 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) family as a catalyst system has been investigated in the presence of molecular oxygen in a batch reactor. It is found that the activity profile of the polymer-supported nitroxyl radicals is in good agreement with that of low-molecular weight nitroxyl catalysts, for example, allylic and benzylic alcohols are oxidised faster than aliphatic alcohols. The oxidations can be tuned to be highly selective such that aldehydes are the only oxidation products observed in the oxidation of primary alcohols and the oxidations of secondary alcohols yield the corresponding ketones. A strong structural effect of the polymeric nitroxyl species on catalytic activity that is dependent upon their spatial orientation of the nitroxyl radicals is particularly noted. The new soluble macromolecular catalysts can be recovered readily from the reaction mixture by solvent precipitation and filtration. In addition, the recycled catalysts demonstrate a similar selectivity with only a small decrease in activity compared to the fresh catalyst even after five repetitive cycles. (c) 2005 Elsevier B.V. All rights reserved.