Alteration of Human Placental Vascular Tone by Antiarrhythmic Medications In Vitro

Antiarrhythmic and Placental Vessels. Introduction : Antiarrhythmic medications are commonly used during pregnancy for treatment of maternal or fetal arrhythmias, but little is known about their effect on human placental vascular tone and, consequently, placental blood flow. The objective of this study was to evaluate the tone responses caused by antiarrhythmic medications in human placental vessels from normal term pregnancies in vitro.
Methods and Results : Isolated human placental arteries and veins from uncomplicated term pregnancies incubated in Krebs'-bicarbonate under 5% oxygen/5% carbon dioxide/balance nitrogen (PO₂ 35 to 38 torr) were exposed to cumulative doses of quinidine, procainamide, lidocaine, flecainide, propranolol, amiodarone, verapamil, digoxin, and adenosine after submaximal contraction with 5-hydroxytryptamine. The study was conducted both in the presence and absence of endothelium. The addition of the tested medications caused a significant, dose-dependent relaxation of human placental arteries and veins except for adenosine, which induced a sustained, dose-dependent contraction of human placental vessels regardless of the presence or absence of tone. Removal of the endothelium did not alter these responses.
Conclusions : Based on these results, the medications tested should have no decremental effect on placental blood flow, with the possible exception of adenosine, which causes significant. dosedependent contraction of human placental vessels in vitro. Should similar contraction be present in vivo, it may have an adverse effect on the fetus when administering adenosine to pregnant women at term or during labor.     

Allocation of attentional resources during habituation to food cues

Two experiments were designed to test the hypothesis that habituation to repeated food cues can be inhibited by allocating processing resources to nonfood cues. In two experiments, the salivary response to 10 presentations of lemon yogurt was assessed while subjects engaged in a controlled cognitive search task (demanding attentional resources), an automatic search task (needing fewer attentional resources), or no task. In Experiment 1, the controlled and automatic search tasks differed in the number of memory set items. In Experiment 2, the size of the memory sets was held constant, and individuals were provided practice to stabilize the different search strategies in the task. The automatic search and no task groups habituated to the repeated presentation of food cues in both experiments, but the controlled search group did not. These results support the hypothesis that allocation of attentional resources to external cues can influence the processing of food cues.     

Telemetry of Programmed and Measured Data in Pacing System Evaluation and Follow-up

Telemetry of programmed and measured data is an important feature of many pacemakers currently used in clinical practice. The ability to receive non-invasive data from the implanted device constitutes a major advantage for the long-term follow-up of the patients and of device performance. There are numerous types of data retrievable via telemetry: parameters of device characteristics (output, battery longevity, impedance, etc), event recorders or counters, event markers, and endocardial electrograms. Ideally, this information should be beneficial in the longitudinal surveilance of modern pacemakers.     

Molecular Interactions between the HSV-1 Capsid Proteins as Measured by the Yeast Two-Hybrid System

HSV-1 B capsids are composed of seven major proteins, designated VP5, VP19C, 21, 22a, VP23, VP24, and VP26. VP indicates that the capsid protein is also a component of the infectious virion. Capsid proteins 21, 22a, and VP24 are specified by a single open reading frame (UL26) that encodes 635 amino acids. An objective of the work in our laboratory is to identify and map interactions among and between capsid proteins. In the present studies we employed the yeast GAL4 two-hybrid system developed by Fields and his colleagues (Nature240, 245–246 (1989)) for this purpose. DNA corresponding to the capsid open reading frames was derived as a PCR product and fused to sequences of the GAL4 activation and DNA binding domains. Using this system each of the capsid proteins has been tested for interactions with all of the other capsid proteins. Three interactions have been identified: a relatively strong self-interaction between 22a molecules (residues 307–635 of UL26), bimolecular interactions between 22a and VP5, and another between VP19C and VP23. The interactions were detected by the expression of β-galactosidase enzyme activity, and yielded 289, 86, and 63 units of enzyme activity, respectively. For the 22a self-interaction, elimination of residues 611–635 resulted in an approximately twofold decrease in enzyme activity. The C-terminal 25 amino acids of 22a were also essential for the bimolecular interaction between 22a and VP5.     

Impact of Nutrients on Cellular Lipid Peroxidation and Antioxidant Defense System

A symposium entitled Impact of Nutrients on Cellular Lipid Peroxidationand Antioxidant Defense System was held at the 33rd Annual Meetingof the Society of Toxicology (SOT) at the Loews Anatole Hotelin Dallas, Texas. The symposium was sponsored by the Food SafetySpecialty Section and focused on the role of particular nutrientsin cellular lipid peroxidation and antioxidant defense system.Emphasis was placed on defining underlying mechanisms for damageand protection, as well as potential ramification in human healthissues. The following are extractions of some of the highlightsfrom each presentation.     

MECHANISMS OF HALOTHANE ADSORPTION BY DRY SODA-LIME

Using fresh soda-lime (15% water by weight) the soda lime/airpartition coefficient of halothane was found to decrease asa function of vapour phase halothane concentration from 2 40at 0.3% halothane by volume to 1.15 at 2.6percnt;, but adsorptiongenerally followed Henry's law. However, soda-lime dried toa constant weight and subsequently exposed to various concentranonsof halothane adsorbed approximately 320 µlitre of vaporizedliquid halothane per 100 g before a measurable concentrationof halothane was detected in the vapour phase. Adding additionalhalothane then caused a linear increase in vapour concentration.We conclude that dry soda-lime can adsorb large quantities ofhalothane by a mechanism which is nimilar to that of a molecularsieve. After these "high affinity" sites are satisfied, additionalhalothane is adsorbed by a mechanism following Henry's law.