Removal and recovery of Cr(VI) from polluted ground waters: a comparative study of ion-exchange technologies.

The focus of this work has been the study of Cr(VI) removal from ground waters and the simultaneous concentration for its reuse using three different technological alternatives: anion-exchange resins, liquid-liquid extraction assisted by hollow fibre membranes and emulsion pertraction. The viability of the considered objectives, i.e.

Studies on the mechanism of intermolecular enyne metathesis: kinetic method and alkyne substituent effects.

The kinetics of enyne metathesis were studied by IR spectroscopy for a variety of alkyne-alkene combinations. The rate law was determined for alkyne-ethylene and alkyne-1-hexene cross metathesis. In the cases examined, greater substitution on the alkyne accelerates the rate of metathesis, and chelation by propargylic esters was ruled out through rate comparison with hydrocarbon alkynes.

Insulin pump therapy, should we consider it more often?

Erratic blood glucose control, hypoglycaemia unawareness and optimisation of glycaemic control during pregnancy are widely recognised indications for commencing diabetic patients on continuous subcutaneous insulin infusion (CSII) using an insulin pump. In patients without such a specific condition, the benefit of CSII over other forms of intensified treatment on glycaemic control and hypoglycaemic rate is generally viewed as too modest to warrant a change of regimen. However, the impact of the treatment regimen on psychosocial parameters is often undervalued, at least in randomised trials.

Aromatic metabolism versus carbon availability: the regulatory network that controls catabolism of less-preferred carbon sources in Escherichia coli.

The current knowledge on the genetics and biochemistry of the catabolism of aromatic compounds in Escherichia coli settles the basis to consider these pathways as a model system to study the complex molecular mechanisms that control the expression of the genes involved in the metabolism of less-preferred carbon sources in this paradigmatic organism. Two different levels of regulation are reviewed: (i) the specific regulatory mechanisms that drive the expression of the catabolic genes when the cognate inducer, i.e.

Hypothesis: Normalisation of cytokine dysbalance explains the favourable effects of strict glucose regulation in the critically ill.

Recent trials investigating the effects of strict glucose regulation in critically ill patients have shown impressive reductions in morbidity and mortality. Although the literature focuses on the possible toxic effects of high blood glucose levels, the underlying mechanism for this improvement is unclear. We hypothesise that strict glucose regulation results in modulation of cytokine production, leading to a shift towards a more anti-inflammatory pattern.

The homogentisate pathway: a central catabolic pathway involved in the degradation of L-phenylalanine, L-tyrosine, and 3-hydroxyphenylacetate in Pseudomonas putida.

Pseudomonas putida metabolizes Phe and Tyr through a peripheral pathway involving hydroxylation of Phe to Tyr (PhhAB), conversion of Tyr into 4-hydroxyphenylpyruvate (TyrB), and formation of homogentisate (Hpd) as the central intermediate. Homogentisate is then catabolized by a central catabolic pathway that involves three enzymes, homogentisate dioxygenase (HmgA), fumarylacetoacetate hydrolase (HmgB), and maleylacetoacetate isomerase (HmgC), finally yielding fumarate and acetoacetate. Whereas the phh, tyr, and hpd genes are not linked in the P.

Discriminative capacity of calcaneal quantitative ultrasound and of osteoporosis and fracture risk factors in postmenopausal women with osteoporotic fractures.

Bone fragility fractures constitute the principal complication of osteoporosis. The identification of individuals at high risk of sustaining osteoporotic fractures is important for implementing preventive measures. The purpose of this study is to analyze the discriminative capacity of a series of osteoporosis and fracture risk factors, and of calcaneal quantitative ultrasound (QUS), in a population of postmenopausal women with a history of osteoporotic fracture.

Plasma metanephrine levels are decreased in type 1 diabetic patients with a severely impaired epinephrine response to hypoglycemia, indicating reduced adrenomedullary stores of epinephrine.

A defective epinephrine response to hypoglycemia is a common disorder in type 1 diabetes. We assessed the role of the adrenomedullary capacity to secrete epinephrine in this disorder by measuring plasma metanephrine levels in affected type 1 diabetic patients compared with those in matched nondiabetic controls. Metanephrine is formed from epinephrine that leaks from adrenomedullary storage vesicles by catechol-O-methyl transferase (COMT) and is continuously released into the circulation.

The PaaX repressor, a link between penicillin G acylase and the phenylacetyl-coenzyme A catabolon of Escherichia coli W.

The pac gene, encoding the penicillin G acylase from Escherichia coli W, is regulated by the PaaX repressor of the phenylacetate catabolic pathway. pac expression depends on the synthesis of phenylacetyl-coenzyme A. PaaX and the cyclic AMP receptor protein (CRP) bind in vitro to the Ppac promoter region.

Molecular determinants of the hpa regulatory system of Escherichia coli: the HpaR repressor.

The HpaR-mediated regulation of the hpa-meta operon (Pg promoter) of the 4-hydroxyphenylacetic acid catabolic pathway of Escherichia coli has been studied. The HpaR regulator was purified to homogeneity showing that it is able to bind selectively to 4-hydroxyphenylacetic, 3-hydroxyphenylacetic and 3,4-dihydroxyphenylacetic acids, which act as inducers of the system. The role of HpaR as a repressor and the requirement for cAMP receptor protein for maximal activity have been confirmed by in vitro transcription analyses.

Antecedent adrenaline attenuates the responsiveness to but not the release of counterregulatory hormones during subsequent hypoglycemia.

Hypoglycemia unawareness is thought to be the consequence of recurrent hypoglycemia, yet the underlying mechanism is still incompletely understood. The aim of the present study was to determine the role of antecedent elevated adrenaline in the pathogenesis of hypoglycemia unawareness. Sixteen healthy volunteers (eight of either sex) participated in two experiments, performed in random order and at least 3 wk apart.

Structural basis for selective recognition of pneumococcal cell wall by modular endolysin from phage Cp-1.

Pneumococcal bacteriophage-encoded lysins are modular choline binding proteins that have been shown to act as enzymatic antimicrobial agents (enzybiotics) against streptococcal infections. Here we present the crystal structures of the free and choline bound states of the Cpl-1 lysin, encoded by the pneumococcal phage Cp-1. While the catalytic module displays an irregular (beta/alpha)(5)beta(3) barrel, the cell wall-anchoring module is formed by six similar choline binding repeats (ChBrs), arranged into two different structural regions: a left-handed superhelical domain configuring two choline binding sites, and a beta sheet domain that contributes in bringing together the whole structure.

Bulky aluminum alkyl scavengers in olefin polymerization with group 4 catalysts.

The binding of H2O to MeAl(OAr)2 (1: Ar = 2,6-di-tert-butyl-4-methylphenyl) in THF-d8 at -40 degrees C provides aquo complex 2, the structure of which was determined by X-ray crystallography. Complex 2 is unstable above 0 degrees C in THF-d8 and decomposes to form ArOH (major), CH4 (minor), and a methyl aluminoxane of undetermined structure. Decomposition of 2 follows first-order kinetics with k = 3.

Hypoglycaemia downregulates endotoxin-induced production of tumour necrosis factor-alpha, but does not affect IL-1beta, IL-6, or IL-10.

The aim of the present study was to investigate the effect of hypoglycaemia on the production capacity of the proinflammatory cytokines tumour necrosis factor-alpha (TNFalpha) and interleukin-1beta (IL-1beta) in subjects with and without diabetes. Hyperinsulinaemic (360 pmolm(-2) x min(-1)) stepped hypoglycaemic (5.0-3.

Effect of 2 weeks of theophylline on glucose counterregulation in patients with type 1 diabetes and unawareness of hypoglycemia.

Background And Objective: A single dose of theophylline improves hypoglycemia unawareness in type 1 diabetic patients. Prolonged theophylline use is, however, associated with emergence of tolerance. This study investigated whether prolonged use of theophylline retains efficacy for counterregulatory defects in patients with type 1 diabetes and hypoglycemia unawareness.

[Natural "dopaminotrophic" cell transplant: a new concept in antiparkinsonian therapy].

Aim And Method: Parkinson s disease is caused by the degeneration of dopaminergic neurons of substantia nigra projecting to striatum. Cellular substitution represents a potentially treatment once beneficial levodopa effects wear off. A promising therapeutic approach is grafting cells or other vectors which release neuroprotective molecules that stimulate regeneration in the damaged nigrostriatal system or, in other words, that exert a dopaminotrophic action.

No vasodilator response to low-dose heparin in the forearm skeletal-muscle vascular bed.

Objective: Recent reports show that heparin induces vasodilation. This heparin-induced vasodilation might interfere with the results of vascular studies using the perfused-forearm technique because the arterial catheter is often flushed with a heparin solution in those experiments. Therefore, we investigated the vascular effects of flushing an arterial catheter with a heparin solution compared with a placebo solution (NaCl 0.

Theophylline improves hypoglycemia unawareness in type 1 diabetes.

Iatrogenic hypoglycemias and the subsequent occurrence of hypoglycemia unawareness are well-known complications of intensive insulin therapy in type 1 diabetic patients that limit glycemic management. From a pharmacological point of view, the adenosine-receptor antagonist theophylline might be beneficial in the management of hypoglycemia unawareness. Theophylline stimulates the release of catecholamines and reduces cerebral blood flow, thereby facilitating stronger metabolic responses to and a prompter perception of decreasing glucose levels.

Caffeine can decrease insulin sensitivity in humans.

Objective: Caffeine is a central stimulant that increases the release of catecholamines. As a component of popular beverages, caffeine is widely used around the world. Its pharmacological effects are predominantly due to adenosine receptor antagonism and include release of catecholamines.

Glucose counterregulation in Type 2 diabetes mellitus.

Glucose counterregulatory failure and hypoglycaemia unawareness frequently complicate treatment of Type 1 diabetes mellitus, especially when aiming for intensive metabolic control. Since tight metabolic control reduces microvascular long-term complications in Type 2 diabetes mellitus, the integrity of glucose counterregulation in Type 2 diabetic patients is important. Using a Medline search, we identified 12 studies in which counterregulatory responses to insulin-induced hypoglycaemia were compared between Type 2 diabetic patients and appropriate controls.

Superimposed levels of regulation of the 4-hydroxyphenylacetate catabolic pathway in Escherichia coli.

The regulation of the Pg promoter, which controls the expression of the meta operon of the 4-hydroxyphenylacetic acid (4-HPA) catabolic pathway of Escherichia coli W, has been examined through in vivo and in vitro experiments. By using Pg-lacZ fusions we have demonstrated that Pg is a promoter only inducible in the stationary phase when cells are grown on glucose as the sole carbon and energy source. This strict catabolite repression control is mediated by the cAMP receptor protein (CRP).

Enhancing desulphurization by engineering a flavin reductase-encoding gene cassette in recombinant biocatalysts.

Biological desulphurization of petroleum feedstocks and products may offer an attractive alternative to reduce sulphur oxide emissions that cause serious environmental pollution. Dibenzothiophene (DBT) desulphurization via the Dsz pathway of Rhodococcus erythropolis IGTS8 is an energetically expensive process that consumes reducing equivalents. We have shown in this work that the HpaC oxidoreductase from Escherichia coli W is able to supply the required FMNH2 to the Dsz monooxygenases.

Functional analysis of the small component of the 4-hydroxyphenylacetate 3-monooxygenase of Escherichia coli W: a prototype of a new Flavin:NAD(P)H reductase subfamily.

Escherichia coli W uses the aromatic compound 4-hydroxyphenylacetate (4-HPA) as a sole source of carbon and energy for growth. The monooxygenase which converts 4-HPA into 3,4-dihydroxyphenylacetate, the first intermediate of the pathway, consists of two components, HpaB (58.7 kDa) and HpaC (18.

Hospital-related outbreak of infection with multidrug-resistant Streptococcus pneumoniae in the Netherlands.

Multidrug-resistant strains of Streptococcus pneumoniae were isolated over a two-year period (July 1995 until August 1997) from the sputum of 36 patients who were hospitalized in a Dutch medical centre. Nosocomial transmission was confirmed by typing of the bacterial isolates: all 36 multidrug-resistant isolates shared the same genotype, serotype, and displayed overlapping drug resistance profiles. Thirty-two of the 36 (89%) patients had chronic obstructive pulmonary disease (COPD).