Physicochemical characterization and tissue distribution of multiple molecular forms of fish (Trachurus trachurus) esterases

1. Tissue-specific electrophoretic patterns of multiple molecular forms of esterases were observed in fish Trachurus trachurus. They were composed of three (in intestine) to nine (in liver) bands characterized mainly as carboxylesterases and acetylesterases. 2. Two major esterase activity bands of pI 4.60 and 4.77 were accompanied by minor ones of higher pH in tissue extracts. 3. Under optimum assay conditions, liver was the richest source of esterase activity followed by intestine, stomach, brain, red muscles, heart, white muscles and gills. 4. Esterases of 70,000 and 420,000 mol. wt were resolved by gel-filtration in liver, intestine and brain. Low size esterases prevailed in liver while the opposite was the case in brain.     

Multiple molecular forms of soluble esterases in the digestive system of the developing chicken

Soluble esterases in tissues of endodermic origin and of various developmental ages of Gallus gallus were analysed by polyacrylamide slab gel electrophoresis and characterized as carboxylesterases, acetylesterases and cholinesterases. Esterase bands were observed from day 9 in the liver and from day 6 in stomach, intestine and yolk sac. The electrophoretic profiles became more complex after hatching with concomitant increase in the staining intensity. On isoelectric focusing of liver extracts only a major form with pI 5.4 was observed. An eserine sensitive band designated EL-1 was found to be tissue (liver) and age (upon hatching) specific. EL-1-like isozymes were also observed in other species of the Galliformes order.     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

Mechanical stability of trees under dynamic loads

Tree stability in windstorms and tree failure are important issues in urban areas where there can be risks of damage to people and property and in forests where wind damage causes economic loss. Current methods of managing trees, including pruning and assessment of mechanical strength, are mainly based on visual assessment or the experience of people such as trained arborists. Only limited data are available to assess tree strength and stability in winds, and most recent methods have used a static approach to estimate loads. Recent research on the measurement of dynamic wind loads and the effect on tree stability is giving a better understanding of how different trees cope with winds. Dynamic loads have been measured on trees with different canopy shapes and branch structures including a palm (Washingtonia robusta), a slender Italian cypress (Cupressus sempervirens) and trees with many branches and broad canopies including hoop pine (Araucaria cunninghamii) and two species of eucalypt (Eucalyptus grandis, E. teretecornus). Results indicate that sway is not a harmonic, but is very complex due to the dynamic interaction of branches. A new dynamic model of a tree is described, incorporating the dynamic structural properties of the trunk and branches. The branch mass contributes a dynamic damping, termed mass damping, which acts to reduce dangerous harmonic sway motion of the trunk and so minimizes loads and increases the mechanical stability of the tree. The results from 12 months of monitoring sway motion and wind loading forces are presented and discussed.     

Peripartum Cardiomyopathy Presenting With Ventricular Tachycardia: A Rare Presentation

A 25-year-old previously asymptomatic pregnant woman at 36 weeks'' gestation was noticed to have repetitive monomorphic ventricular tachycardia. A dilated left ventricle with moderately reduced systolic function was found on echocardiographic examination. This is a very rare presentation of peripartum cardiomyopathy (PPCMP) presenting with repetitive monomorphic ventricular tachycardia.     

Measurement of dexfenfluramine metabolism in rat liver microsomes by gas chromatography–mass spectrometry

A specific and useful method was developed for the determination of dexfenfluramine metabolism by microsomal systems utilising GC–MS. The synthesis of two metabolites 1-(3-trifluoromethylphenyl)propan-2-ol (‘alcohol') and 1-(3-trifluoromethylphenyl)-1,2-propanediol (‘diol') via straightforward routes, were confirmed by MS and NMR spectra. The conditions for extraction from alkalinised microsomal mixtures of the metabolites nordexfenfluramine, 1-(3-trifluoromethylphenyl)propan-2-one (‘ketone'), alcohol and diol, their conversion to trifluoroacetate derivatives and analysis by GC–MS–SIM are described. Calibration curves were constructed between 48 and 9662 nM and fitted to quadratic equations (r²>0.999). The method precision was good over low (121 nM) medium (2415 nM) and above medium (9662 nM) concentrations for all metabolites; the within- and day-to-day coefficients of variation ranged between 2.5–12.4% and 6.7–17.5%, respectively. The accuracy, measured as bias, was very good both within- and day-to-day (range: −0.4–12.6%, 0.8–18.9%). For most metabolites, the C.V. for the assay and bias increased at 121 nM. Dexfenfluramine metabolism by rat liver microsomes was investigated using the assay method and showed a concentration dependent increase in nordexfenfluramine and ketone metabolites over the substrate range of 5–200 μM.     

A recently silenced, duplicate PgiC locus in Clarkia

Previous electrophoretic analysis showed that 17 diploid species of the wildflower Clarkia (Onagraceae) have two cytosolic isozymes of phosphoglucose isomerase (PGIC; EC 5.3.1.9), whereas 15 other diploid species have a single PGIC. Molecular studies revealed that the two isozymes in the former species are encoded by duplicate genes, PgiC1 and PgiC2, whereas the single isozyme in the latter is always encoded by PgiC1. Phylogenetic analysis of the nucleotide sequences implied that PgiC2 was silenced four times independently in the genus. Here we describe a psi PgiC2 from C. mildrediae, a species in which only PgiC1 is expressed. The discovery of the psi PgiC2 is significant because it confirms a formal prediction of the phylogenetic analysis. The psi PgiC2 includes 5,039 nucleotides corresponding to 18 of the 23 exons of PgiC, as well as the intervening introns and 3' nontranslated region. The absence of an increase of nucleotide substitutions in its "exons" suggests that the gene was silenced recently. The present study appears to be the first to establish that a specific duplicate gene locus regularly expressed in a group of related plant species has been silenced in one of them. The multiple independent silencings of PgiC2 suggest that it remained functional but inessential in ancestral lineages. We discuss the possibility that PgiC2 may have been preserved in these lineages by selection against mutants causing defective PGIC1- PGIC2 heterodimers.