Restriction enzyme cleavage maps of mitochondrial DNA from the Spanish honeybee, Apis mellifera iberica (Hymenoptera: Apidae), were compared with those from the European subspecies A. m. mellifera, A. m. ligustica, and A. m. carnica, and the African subspecies A. m. intermissa and A. m. scutellata. The mitochondrial DNA (mtDNA) of the two African subspecies can be distinguished by restriction fragment polymorphisms revealed by Hinf I digests. Two distinct mtDNA types were found among Spanish honeybees: a west European mellifera-like type, which predominates in the north of Spain, and an African intermissa-like type, which predominates in the south. Spain appears to be a region of contact and hybridization between the two subspecies A. m. intermissa and A. m. mellifera, which respectively represent African and west European honeybee lineages. This natural boundary between European and African honeybee populations in the Old World may provide a model for predicting the eventual outcome of the colonization of North America by introduced African honeybees.

Africa↗

PubMedDate not supplied

Cost-benefit analysis of unit dose drug distribution systems: a conceptual approach.

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Costs and Cost Analysis↗

PubMedDate not supplied

Cardioplegia for heart transplantation: unmodified UW solution compared with Stanford solution.

Clinical practice and laboratory studies have demonstrated the efficacy of cold crystalloid cardioplegia for donor heart protection. Efforts to increase the margin of safety for protection led us to compare unmodified University of Wisconsin (UW) solution to the dextrose, mannitol-based Stanford (ST) solution. A canine model of heart transplantation with antegrade hypothermic cardioplegic arrest and 6 hours of 4 degrees C ischemic storage was used. An oxygenated blood-primed isolated heart preparation was used for reperfusion and myocardial mechanics and energetics studies of the working heart. Six of 6 UW and 4 of 6 ST hearts reached the working phase. Computer-assisted analysis of pressure-volume loops generated at varying flows measured by tri-axial sonomicrometry and high-fidelity micromanometry showed no significant differences in function between the ST and UW groups by maximum elastance (UW, 4.2 +/- 1.1; ST, 4.0 +/- 0.7), preload recruitable stroke work (UW, 43.7 +/- 7.3; ST, 43.4 +/- 8.7), or slope of log-linear end-diastolic pressure-volume curve (UW, 0.057 +/- 0.01, ST, 0.061 +/- 0.01). Specimens for determination of myocardial water content were taken after cardioplegic arrest, after storage, after reperfusion, and after the working phase. There was a significant increase in tissue water after reperfusion in both groups (UW, 75.7% +/- 0.5% to 81.6% +/- 0.2%, p = 0.0001; ST, 76.5% +/- 0.4% to 83.4% +/- 0.3%, p = 0.0002), which persisted after the working phase (UW, 81.5% +/- 0.9%, p = 0.0002; ST, 82.6% +/- 0.1%, p = 0.0003). Both groups exhibited postreperfusion increase in myocardial water content, but this edema was significantly less marked in the UW group (p = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗

PubMedDate not supplied

Placement of aortic valve bioprostheses in sheep via a left thoracotomy. Implantation of stentless porcine heterografts.

Juvenile sheep provide a good model for assessing the efficacy of antimineralization techniques because of their rapid calcification of bioprosthetic valves. Stentless bioprosthetic valves are under evaluation for possible improved durability as aortic valve replacements. A left thoracotomy approach for aortic valve implantation, which facilitates intraoperative and postoperative hemodynamic data collection, has been developed and refined in 13 sheep. A critical feature of this technique is a partial rib resection that creates a soft tissue acoustic window to improve postoperative transthoracic echocardiographic examination. This allows both quantification of valvular gradients and qualitative assessment of valve leaflet motion and calcification. Excellent correlation was observed between the intraoperative invasive valvular gradients and the postoperative echocardiographic gradients available in four animals (mean gradient r = 0.96, p = 0.003; peak gradient r = 0.98, p = 0.0004). This is an excellent technique for serial postoperative noninvasive evaluation of valve prostheses implanted in the aortic position.

Animals↗