Mobilization of manufactured gas plant tar with alkaline flushing solutions

This experimental study investigates the use of alkaline and alkaline-polymer solutions for the mobilization of former manufactured gas plant (FMGP) tars. Tar-aqueous interfacial tensions (IFTs) and contact angles were measured, and column flushing experiments were conducted. NaOH solutions (0.01-1 wt.%) were found to significantly reduce tar-aqueous IFT. Contact angles indicated a shift to strongly water-wet, then to tar-wet conditions as NaOH concentration increased. Column experiments were conducted with flushing solutions containing 0.2, 0.35, and 0.5% NaOH, both with and without xanthan gum (XG). Between 10 and 44% of the residual tar was removed by solutions containing only NaOH, while solutions containing both NaOH and XG removed 81-93% of the tar with final tar saturations as low as 0.018. The mechanism responsible for the tar removal is likely a combination of reduced IFT, a favorable viscosity ratio, and tar bank formation. Such an approach may have practical applications and would be significantly less expensive than surfactant-based methods.     

Lateral diffusion in planar lipid bilayers

Direct measurements by fluorescence correlation spectroscopy of lateral diffusion coefficients of fluorescent lipid analogs in lipid bilaryer membranes indicate self-diffusion coefficients D greater than 10(-7) square centimeters per second for various lipid systems above their reported transition temperatures. Cholesterol in egg lecithin at mole ratio of 1 : 2 reduces D by about twofold, while retained hydrocarbon solvent can increase it by two- to threefold.     

The application of radionuclide infarct scintigraphy to diagnose perioperative myocardial infarction following revascularization

To evaluate the application of radionuclide infarct scintigraphy to diagnose myocardial infarction after revascularization, we obtained postoperative technetium 99m pyrophosphate myocardial scintigrams, serial electrocardiograms and CPK-MB isoenzymes in ten control and 51 revascularized patients. All control patients had negative electrocardiograms and scintigrams, but eight had positive isoenzymes. Eight revascularized patients had positive electrocardiograms, images and enzymes and two had positive scintigrams and enzymes with negative electrocardiograms. Thirty-four patients with negative electorcardiograms and scintigrams had positive isoenzymes; in only seven patients were all tests negative. Our data suggest radionuclide infarct scintigraphy is a useful adjunct to the electrocardiogram in diagnosing perioperative infarction. The frequent presence of CPK-MB in postoperative patients without other evidence of infarction suggests that further studies are required to identify all factors responsible for its release.     

Inhibition and alternate-substrate studies on the mechanism of malic enzyme

A number of dead-end inhibitors and alternate substrates were examined to gain an understanding of the substrate specificity and mechanism of malic enzyme. Comparison of Ki values for competitive inhibitors suggested that binding of the l-carboxyl of L-malate is by ion pairing with lysine or arginine, while binding of the 4-carboxyl is weaker, and probably of the induced-dipolar type. The 2-hydroxyl hydrogen bonds to a catalytic group, which, when it is protonated, adsorbs the keto form of oxalacetate. Since the only molecule other than L-malate that is oxidized is L-malate-beta-amide, carbon 4 must be trigonal for substrate activity, although a tetrahedral carbon bearing one or two hydroxyl groups gives good binding. Hydroxy groups at carbon 3 contribute to binding, but prevent substrate activity. Hydroxy and ketomalonates are bound more strongly than any of the four carbon acids, suggesting that the latter are bound with some strain. In inhibition studies, pyruvate analogues were competitive vs. pyruvate but noncompetitive vs. malate, while malate analogues were competitive vs. malate and noncompetitive vs. pyruvate. These compounds thus bind to both enzyme-triphosphopyridine nucleotide (E-TPN) and enzyme-reduced triphosphopyridine nucleotide (E-TPNH), but only malate analogues prevent release of TPN, while pyruvate analogues prevent release of TPNH. Ketomalonate and oxalacetate, both of which are slowly reduced by the enzyme in the presence of TPNH and thus must combine in the keto form with E-TPNH,, appear to combine with E-TPN mainly in the gem-diol (or for oxalacetate, also the enol) form. The substrate for the decarboxylation of oxalacetate at pH 4.5 is the keto form.     

Survival in neonatal biventricular repair of left-sided cardiac obstructive lesions associated with hypoplastic left ventricle

Patients with left ventricular hypoplasia and left-sided heart obstructive lesions other than critical aortic stenosis may be inappropriately subjected to single ventricular repair because their assessment is based on faulty qualitative evaluations or on quantitative methods developed for critical aortic stenosis. Patients with left ventricular hypoplasia and left-sided heart obstructions other than critical aortic stenosis successfully underwent biventricular repair despite "failing" to pass established criteria for critical aortic stenosis.     

The expanding small heat-shock protein family, and structure predictions of the conserved "alpha-crystallin domain"

The ever-increasing number of proteins identified as belonging to the family of small heat-shock proteins (shsps) and alpha-crystallins enables us to reassess the phylogeny of this ubiquitous protein family. While the prokaryotic and fungal representatives are not properly resolved, most of the plant and animal shsps and related proteins are clearly grouped in distinct clades, reflecting a history of repeated gene duplications. The members of the shsp family are characterized by the presence of a conserved homologous "alpha-crystallin domain," which sometimes is present in duplicate. Predictions are made of secondary structure and solvent accessibility of this domain, which together with hydropathy profiles and intron positions support the presence of two similar hydrophobic beta-sheet-rich motifs, connected by a hydrophilic alpha-helical region. Together with an overview of the newly characterized members of the shsp family, these data help to define this family as being involved as stable structural proteins and as molecular chaperones during normal development and induced under pathological and stressful conditions.     

A new clinical classification for hospital prognosis of unstable angina pectoris

Unstable angina represents a heterogeneous spectrum of clinical entities between chronic stable angina and acute myocardial infarction. To facilitate prognostication of in-hospital outcome, we prospectively tested on a priori unstable angina classification scheme based on information available at the time of acute presentation. Prospective database enrollment at the time of emergency room presentation was performed and patients were classified into 1 of the following categories: class IA, acceleration of previous exertional angina without electrocardiographic (ECG) changes; class IB, acceleration of previous exertional angina with ECG changes; class II, new-onset exertional angina; class III, new-onset rest angina; class IV, protracted rest angina with ECG changes. The study consisted of 1,387 consecutive patients with unstable angina. Baseline demographics and aggregate in-hospital major cardiac event rates were recorded (myocardial infarction, refractory angina, and death). There was a significant increasing trend in cardiac events from class I to IV (p < 0.0001). Class IA patients had the lowest aggregate event rate at 2.7% (p = 0.0005). Paired chi-square tests of adjacent categories showed no differences in event rates for class IB and II (p = 0.3). A significantly higher rate of adverse events was seen for class III patients (20.1%, p < 0.0001). Class IV patients demonstrated the highest rate of in-hospital adverse events (42.8%, p < 0.0001). We conclude that this easily deduced, universally applicable categorization of unstable angina is highly prognostic of in-hospital adverse cardiac events and hence could have potential use for triage decisions regarding hospital admission and intensity of therapy.