Effects of diltiazem on reperfusion-induced arrhythmias in vitro and in vivo.

The effects of the calcium antagonist, diltiazem, on myocardial injury during ischemia and reperfusion were studied both in vitro, in the isolated rat heart, and in vivo, in a closed-chest pig model. In the isolated rat heart, administration of diltiazem before or at the onset of ischemia resulted in a dose-dependent reduction of the incidence and duration of ventricular fibrillation. This reduction was associated with a dose-dependent reduction in overflow of ATP catabolites (adenosine, inosine, hypoxanthine and xanthine).

Alternative matrix seriation, traditional seriation, and multiple classification.

This study investigated the structural relationships between traditional seriation tasks derived from Piaget's publications and alternative matrix seriation on the one hand, and alternative matrix seriation and multiple classification on the other. Subjects were 464 children from two kindergartens and three primary schools, Grades 1 through 6 who completed these three types of tasks. Factor analysis revealed that the alternative matrix seriation tasks (often used in neo-Piagetian research) did not reflect the same underlying concept as the traditional seriation tasks derived from Piaget's publications.

Concentration-dependent protection by captopril against ischemia-reperfusion injury in the isolated rat heart.

The purpose of this study was to investigate the protective effects of captopril at three concentrations (1, 10 and 80 micrograms/ml) against reperfusion injury after 15 min of coronary ligation in the isolated perfused rat heart. During ischemia, the apex displacement (AD) and pressure rate index (PI) decreased markedly and only in the presence of 80 micrograms captopril less reduction of the PI was obtained (p less than 0.05).

Effects of intravenous captopril on inducible sustained ventricular tachycardia one week after experimental infarction in the anaesthetized pig.

The effect of captopril on inducible sustained ventricular tachycardia (VT) one week after myocardial infarction was studied in 6 Yorkshire swine. In 24 pigs, controlled myocardial infarction (MI) was produced by reversible occlusion of the left anterior descending artery during 60 minutes using an inflatable balloon catheter. Four animals died during this procedure and another 4 during the first week.

Heat-labile enterotoxin of Escherichia coli. Characterization of different crystal forms.

Heat-labile enterotoxin (LT) was obtained in large quantities (several-gram amounts) and great purity from Escherichia coli C600 carrying the LT-coding multicopy plasmid EWD299. By growing this strain on a medium that allows high cell densities in the early stationary phase, we increased the net LT production per milliliter by a factor of 200, compared to natural porcine enterotoxigenic E. coli.

Storage-retrieval processes of normal and learning-disabled children: a stages-of-learning analysis of picture-word effects.

Previous research comparing acquisition performance of learning-disabled and normally achieving children has led to the suggestion that the locus of memory differences lies in either the storage or retrieval components of recall. In this paper we report a free-recall experiment in which a new stages-of-learning model was used to examine the effects of a picture-word manipulation on storage and retrieval differences between nondisabled and disabled grade 2 and 6 children. Although the results of this experiment were consistent with the idea that disabled students are poorer at memory tasks than nondisabled students, the stages-of-learning analysis provided information regarding the precise locus of the deficiencies.

Value of lead V4R in exercise testing to predict proximal stenosis of the right coronary artery.

To assess the value of lead V4R during exercise testing for predicting proximal stenosis of the right coronary artery, 107 patients were studied. In all patients, a Bruce exercise test with the simultaneous recording of leads I, II, V4R, V1, V4 and V6 was followed by coronary angiography. Apart from registering ST segment changes in the conventional leads, all patients were classified according to absence or presence of an ST segment deviation of 1 mm or greater in lead V4R.

Haemodynamic and antiarrhythmic effects of intravenous flecainide acetate in chronic congestive heart failure.

The objective of this study was to evaluate the haemodynamic and antiarrhythmic effects of flecainide acetate in patients with heart failure. Flecainide acetate, a class Ic antiarrhythmic agent, was given intravenously to 9 patients with congestive heart failure and frequent ventricular arrhythmias with nonsustained ventricular tachycardia. The drug (2 mg/kg) was infused slowly over 60 minutes.

Captopril reduces purine loss and reperfusion arrhythmias in the rat heart after coronary artery occlusion.

Captopril was perfused through isolated rat hearts; its effects after local ischemia and reperfusion were assessed. Upon reperfusion all untreated (10 out of 10) but only 4 (out of 10) captopril-treated (80 micrograms/ml) hearts fibrillated (P less than 0.02).

Heart rate-dependent atrioventricular nodal conduction and the effects of calcium channel blocking drugs: comparison of verapamil and nifedipine.

We compared the effects of the calcium channel blocking drugs verapamil and nifedipine on atrioventricular (AV) nodal function by His bundle electrocardiography in 24 pigs. AV nodal conduction time was decreased 16% by nifedipine (0.1 mg/kg + 3 micrograms/kg/min; p less than 0.

A Comparison of Four Methods of Scaling for the Acquisition of Early Number Concept.

Four different methods of scaling for constructing a developmental scale of early number concept were compared: the Guttman scale analysis, the stochastic Mokken scale analysis, the ordering theoretic method, and the item tree analysis. Ss were 537 kindergarten and Grade 1 primary school children who were given three types of number comparison tasks, linear, linear-nonlinear, and nonlinear. The stochastic Mokken scale analysis was the most suitable one for constructing a developmental scale of these number comparison tasks.

Hemodynamic effects of high dosages of verapamil and the lack of protection by 4-aminopyridine in the rabbit.

4-Aminopyridine (1 mg/kg) restored a 35% fall in arterial blood pressure in rabbits evoked by a verapamil infusion (0.5 mg/kg/min) more effectively than calcium-levulate (approx. 13 mg/kg).

Characterization of intracellular inclusions formed by Pseudomonas oleovorans during growth on octane.

The growth of Pseudomonas oleovorans on n-octane was characterized by the formation of intracellular structures. These inclusions were isolated and characterized. Morphologically, they resembled the poly-beta-hydroxybutyrate granules found in Bacillus cereus, as shown by freeze-fracture electron microscopy.

Some Behavioral Characteristics of the Partial Seriators Reconsidered.

In this study the effects of the use of some of Piaget's criteria to make a distinction between partial and operational seriators were investigated. Therefore, attention was paid to three behaviorial characteristics in which the child constructed the series: concatenated transitive comparisons, the verification of transitive comparisons, and the number of self-corrections. Ss were 428 children from kindergarten and primary school, grades 1 to 6, who were observed while completing a set of six seriation tasks derived from Piaget's publications.

Preliminary studies on experimentally induced calcification of femoral arteries in the rat.

Ligatured segments of femoral artery were incubated in vivo and examined after 15 days. Microscopic observation of these arterial segments showed medial calcification. Initial deposition of calcium occurs in the internal elastic lamina.

Growth of iron-oxidizing thiobacilli in the presence of chalcopyrite and galena.

Iron-oxidizing thiobacilli were adapted to grow on a chalcopyrite and a galena ore concentrate. When grown on the chalcopyrite concentrate, the bacteria exhibited a doubling time of 38.4 +/- 2.

Autotrophic Growth of Thiobacillus acidophilus in the Presence of a Surface-Active Agent, Tween 80.

Cellular protein, pH, dissolved oxygen concentration, and static surface tension were measured during growth of Thiobacillus acidophilus on elemental sulfur in the absence and presence of up to 5,000 mg of Tween 80 per liter. The decrease in pH and the increase in sulfate production were observed to be less accurate measurements of growth when compared with the increase in cellular protein. The doubling time of the bacterium decreased approximately 50% with the addition of 500 mg of Tween 80 per liter.

Nature of the regions involved in the insertion of newly synthesized protein into the outer membrane of Escherichia coli.

Outer membrane proteins are synthesized by cytoplasmic membrane-bound polysomes, and inserted at insertion sites which cover about 10% of the total outer membrane when cells grow with a generation time of 1 h. A membrane fraction enriched in outer membrane insertion regions was isolated and partly characterized. The rat at which newly inserted proteins are transferred from such insertion regions into the rest of the outer membrane was found to be very fast; the new protein content of insertion regions and that of the remaining outer membrane equilibrate completely within about 20 s at 25 degrees C.

Insertion of newly synthesized proteins into the outer membrane of Escherichia coli.

The insertion of newly synthesized proteins into the outer membrane of Escherichia coli has been examined. The results show that there is no precurser pool of outer membrane proteins in the cytoplasmic membrane because first, the incorporation of a [35S]methionine pulse into outer membrane proteins completely parallels its incorporation into cytoplasmic membrane proteins, and second, under optimal isolation conditions, no outer membrane proteins are found in the cytoplasmic membrane, even when the membranes are analysed after being labeled for only 15 s. The [35S]methionine present in the outer membrane after a pulse of 15 s was found in protein fragments of varying sizes rather than in specific outer membrane proteins.

Effects of an aminosteroid, ORG 6001, on various membrane phenomena of non-myelinated nerve fibres of the rat.

The aminosteroid ORG 6001 (3 alpha-amino-5 alpha-androstan-2 beta-ol-17-one hydrochloride) was shown to be a compound with a rather strong local anaesthetic action. Compound action potentials evoked in non-myelinated nerve fibres of the desheathed rat vagus with the single sucrose gap method showed, in presence of this drug, a decrease in amplitude and increase in conduction time comparable with the effect of lidocaine. Since the total membrane resistance represented by the amplitude of the electrotonic potential was not affected by ORG 6001, it is likely that ORG 6001 reduces the transient increase in sodium conductance during the action potential, a mechanism also postulated for lidocaine.

The effect of toluene on the structure and permeability of the outer and cytoplasmic membranes of Escherichia coli.

The effect of toluene on Escherichia coli has been examined. In the presence of Mg2+, toluene removes very little protein, phospholipid, or lipopolysacharide from E. coli.