Alleviation of postanesthetic hypoxemia in the horse

This study was designed to investigate the effect of the nasotracheal insufflation of oxygen at a flow rate of 15 L/min on the arterial partial pressure of oxygen during the recovery period following inhalation anesthesia in the horse. It has been stated that this is a suitable flow rate to prevent postoperative hypoxemia but without any experimental evidence to support those statements. Horses being used for the study of healing of cartilage were anesthetized on two separate occasions. Following one period of anesthesia they were allowed to recover breathing room air, and following the other period of anesthesia oxygen was insufflated into the trachea at 15 L/min throughout the recovery period. This permitted each horse to act as its own control and allowed statistical analysis using Student's t-test for paired samples.

The insufflated horses had a higher arterial partial pressure of oxygen during the recovery period than did the noninsufflated horses (p < 0.05).

     

Comparison of the cardiopulmonary effects of anesthesia maintained by continuous infusion of romifidine,guaifenesin, and ketamine with anesthesia maintained by inhalation of halothane in horses

OBJECTIVE: To compare cardiopulmonary responses during anesthesia maintained with halothane and responses during anesthesia maintained by use of a total intravenous anesthetic (TIVA) regimen in horses. ANIMALS: 7 healthy adult horses (1 female, 6 geldings). PROCEDURE: Each horse was anesthetized twice. Romifidine was administered IV, and anesthesia was induced by IV administration of ketamine. Anesthesia was maintained for 75 minutes by administration of halothane (HA) or IV infusion of romifidine, guaifenesin, and ketamine (TIVA). The order for TIVA or HA was randomized. Cardiopulmonary variables were measured 40, 60, and 75 minutes after the start of HA orTIVA. RESULTS: Systolic, diastolic, and mean carotid arterial pressures, velocity time integral, and peak acceleration of aortic blood flow were greater, and systolic, diastolic, and mean pulmonary arterial pressure were lower at all time points for TIVA than for HA. Pre-ejection period was shorter and ejection time was longer for TIVA than for HA. Heart rate was greater for HA at 60 minutes. Minute ventilation and alveolar ventilation were greater and inspiratory time was longer for TIVA than for HA at 75 minutes. The PaCO2 was higher at 60 and 75 minutes for HA than forTIVA. CONCLUSIONS AND CLINICAL RELEVANCE: Horses receiving a constant-rate infusion of romifidine, guaifenesin, and ketamine maintained higher arterial blood pressures than when they were administered HA. There was some indication that left ventricular function may be better during TIVA, but influences of preload and afterload on measured variables could account for some of these differences.     

Genome Size Variation in Maize Populations Selected for Cold Tolerance

Previous studies have indicated a relationship between genome size and cold tolerance in plants. Many species adapted to growth in cool environments have large genome sizes. These studies are based on interspecific DNA content variation. In this study, the nuclear DNA content of eight maize populations was determined. These populations were obtained from the University of Nebraska and represent populations selected for cold tolerance and their respective unselected original populations. Intraspecific DNA content variation was observed between the selected and unselected populations. Upon assessing the data based solely on cold tolerance, no clear relationship between genome size and cold tolerance was apparent. When both freeze tolerance and cold tolerance were considered, populations which were cold tolerant and exhibited a certain degree of freeze tolerance were observed to have significantly larger genomes relative to the unselected populations. Thus, it appears that the relationship between intraspecific genome size variation and cold tolerance is similar to the relationship between interspecific genome size variation and growth at cooler temperatures in plants.     

"Coulomb Staircase" at Room Temperature in a Self-Assembled Molecular Nanostructure

Double-ended aryl dithiols [alpha,alpha'-xylyldithiol (XYL) and 4,4'-biphenyldithiol] formed self-assembled monolayers (SAMs) on gold(111) substrates and were used to tether nanometer-sized gold clusters deposited from a cluster beam. An ultrahigh-vacuum scanning tunneling microscope was used to image these nanostructures and to measure their current-voltage characteristics as a function of the separation between the probe tip and the metal cluster. At room temperature, when the tip was positioned over a cluster bonded to the XYL SAM, the current-voltage data showed "Coulomb staircase" behavior. These data are in good agreement with semiclassical predictions for correlated single-electron tunneling and permit estimation of the electrical resistance of a single XYL molecule (approximately18 ± 12 megohms).     

Probing the Local Effects of Magnetic Impurities on Superconductivity

The local effects of isolated magnetic adatoms on the electronic properties of the surface of a superconductor were studied with a low-temperature scanning tunneling microscope. Tunneling spectra obtained near magnetic adsorbates reveal the presence of excitations within the superconductor's energy gap that can be detected over a few atomic diameters around the impurity at the surface. These excitations are locally asymmetric with respect to tunneling of electrons and holes. A model calculation based on the Bogoliubov-de Gennes equations can be used to understand the details of the local tunneling spectra.     

INADVERTENT INTRATHECAL ADMINISTRATION OF DIATRIZOATE MEGLUMINE AND DIATRIZOATE SODIUM DURING MYELOGRAPHY IN A DOG

A dog undergoing diagnostic myelography inadvertently received 0.5 ml diatrizoate meglumine (66%) and (10%) diatrizoate sodium via intrathecal injection. This resulted in post-operative seizures requiring extended sedation of the patient. The clinical course and management of this patient are presented. Complications associated with the inappropriate administration of a hyperosmolar contrast agent into the subarachnoid space and the results of similar accidents in humans are also discussed. The dog in the report recovered with no evidence of long trem neurological dam