Normal values and commonly used echocardiographic formulae for adults.

Echocardiography is a valuable and widespread clinical and research tool. The normal parameters and formulae for adults are widely dispersed throughout the medical literature. The purpose of this paper is to present, in a single source, the already acquired normal values and formulae used in the field.

Transmission and scanning electron microscopy of cell monolayers grown on polymethylpentene coverslips.

Plastic coverslips made of polymethylpentene serve as excellent substrates for growth of bovine endothelial cells, and are easily processed for both transmission (TEM) and scanning (SEM) electron microscopy. Portions of the same coverslip (monolayer) are used for both SEM and TEM examination and are fixed, postfixed, and dehydrated as a single entity. The portion of the coverslip for SEM is then excised, critical point dried, and mounted for sputter coating prior to viewing. The remaining piece of coverslip used for TEM is Epon-Araldite embedded, polymerized, separated from the coverslip by liquid nitrogen immersion, and sectioned either "en face" or in cross section for viewing. Coated glass coverslips are not required and organic solvents such as propylene oxide, acetone, and amyl acetate can be used for dehydration and infiltration. Furthermore, specimens do not require re-embedding or blocks to be glued onto blank capsules before sectioning. The number of cells needed to achieve a monolayer is significantly reduced compared to the usual culture flasks, but are abundant enough to assess ultrastructural changes accurately. Support films may be required to prevent folding of the ultrathin section which can obstruct viewing of cells located on the edge of the section.

In vitro model for the study of platelet-vessel wall interactions following a freeze- thaw injury.

Platelet-endothelial cell interactions are important for maintaining normal hemodynamics. The intact endothelial cell lining is considered nonthrombogenic, but following disruption of the lining, platelets bind to the subendothelium. There is also much conjecture concerning the affinity of platelets for damaged endothelial cells. A model is described for the study of platelet-aorta vessel wall interactions following freeze-thaw insult. Using this model, we found that control aortas (37 degrees C) perfused with platelet-rich plasma or gel-filtered platelets showed no generalized platelet-endothelial cell interactions, although some platelets did adhere to areas of exposed subendothelium. Following freeze-thaw insult (-15 degrees or -20 degrees C), the endothelial lining was grossly disrupted. The remaining endothelium was severely damaged, demonstrating holes and pits in the plasma membranes and separation of adjacent cell borders. Platelets readily adhered to the basal lamina but were rarely noted in sole contact with the damaged endothelium. Platelet binding did not result in morphologic changes, degranulation, or aggregation. Using transmission electron microscopy, we noted platelets in contact with amorphous material and microfibrils but not collagen fibers of the subendothelium. It is concluded that this model is suitable for the in vitro study of certain hemodynamic phenomena associated with blood vessel freeze-thaw injury. In addition, freeze-thaw damage in this in vitro model indicated that platelet-vessel wall interactions were limited to areas of exposed subendothelium.

Characterization of freeze-thaw induced ultrastructural damage to endothelial cells in vitro.

The pathophysiology of endothelial cells is important to a variety of vascular conditions including coagulation and hemostasis resulting from clinical frostbite. Use of an in vitro model system demonstrated that when bovine endothelial cells were frozen at 1 degrees C or 20 degrees C/min and thawed immediately (20 degrees C/min), a variety of ultrastructural alterations occurred. Membranous structures were most extensively damaged, with mitochondria the most sensitive organelle. Low amplitude mitochondrial swelling, first evident at 0 degrees C, progressed to high amplitude swelling by -10 degrees C (frozen). In addition, the rough endoplasmic reticulum was dilated and formed large vesicles with a homogeneous matrix. Nuclear changes first occurred at -15 degrees C. These included separation and distortion of the nuclear membrane, changes in chromatin distribution, and disruption of the nucleolus. Scanning electron microscopy revealed perforated plasma membranes in some cells at -10 degrees C (frozen) and in most cells by -20 degrees C. Cultures frozen at 20 degrees C/min revealed mostly the same ultrastructural damage noted at 1 degrees C/min except a higher percentage of cells exhibited alterations. Data from the recovery index and lactic dehydrogenase (LDH) release correlated well with observed ultrastructural changes. Early swelling of mitochondria and dilation of rough endoplasmic reticulum was not lethal in the absence of freezing. Increased swelling in cytoplasmic organelles coupled with nuclear alterations at -15 degrees C resulted in a decreased survival rate and release of significant quantities of LDH by -20 degrees C. No unique morphological changes were temperature specific, but the total number of cells that displayed alterations increased as temperature decreased.

Platelet-endothelial cell interactions in vitro following freeze-thaw injury or detergent treatment.

Platelet interactions with cultured bovine endothelial cells were studied following freeze-thaw damage or detergent treatment. Platelets from whole blood, platelet-rich plasma, or gel-filtered plasma did not interact directly with freeze-thaw-damaged endothelial cells. Freezing and thawing did result in the exposure of an extracellular matrix located beneath the cells, which proved very thrombogenic. Platelets from all sources attached to both microfilament and amorphous components of the extracellular matrix, although only platelets from whole blood demonstrated aggregation and extensive pseudopodia formation. Treatment of cells with Triton-X detergent resulted in exposure of an intracellular cytoskeleton. Most platelets attached to the cytoskeleton were located near the cell border and had one or more pseudopodia either in contact with extracellular or intracellular material. Adhesion of platelets to the extracellular matrix may represent platelet-collagen or platelet-fibronectin interactions since both are produced by an incorporated into the extracellular matrix. Platelet interaction with endothelial cytoskeletons may represent contact of pseudopodia with the now exposed matrix located beneath the cells. The possibility that platelets also adhered to intracellular components could not be eliminated. These findings are in agreement with data from a freeze-thaw injury model of perfused aorta. In addition, they tend to indicate that physical insult is not sufficient to induce platelet interaction with the endothelial surface, but that chemical modification enhances platelet deposition.