Assisted venous drainage, venous air, and gaseous microemboli transmission into the arterial line: an in-vitro study.

The objective of this study was to examine the interaction of cardiopulmonary bypass venous air with assisted venous drainage, focusing on its production of gaseous microemboli in the arterial line. An in-vitro recirculating cardiopulmonary bypass circuit containing fresh whole bovine blood was monitored with a pulsed-doppler microbubble detector. Air of specific amounts was injected into the venous line and gaseous microemboli counts were obtained distal to the arterial filter. Data was recorded for unassisted drainage, vacuum-assisted drainage, and centrifugal pump-assisted drainage. Centrifugal pump-assisted drainage produced over 300 microbubbles in one minute distal to the arterial filter when venous air was introduced into the circuit. Of these, 220 were greater than 80 microns in size. Vacuum-assisted drainage produced no microbubbles when the same amount of venous air was introduced into the circuit. However, vacuum-assisted drainage did produce some microbubbles in the arterial line when a stopcock was left open on the venous line for 30 seconds. Unassisted drainage produced no microbubbles at all levels of venous air entrainment. Air becomes entrained in the venous line from a variety of sources. In a typical gravity-drained situation, the air remains whole and is dissipated in the venous reservoir by buoyancy and filtration. In an assisted-drainage situation, the air is subjected to additional forces. The air is subjected to a greater degree of negative pressure and, with centrifugal pump assisted drainage, is subjected to kinetic energy imparted by the cones or vanes of the pump. The kinetic energy from the centrifugal pump appears to break the air into small bubbles which become suspended in the blood, passing through the reservoir, oxygenator, and arterial filter. In a clinical setting, these bubbles would be passed into a patient's arterial system.

Contribution of serum ethanol concentration to the osmol gap: a prospective volunteer study.

BACKGROUND: The contribution of ethanol ([EtOH]) to the osmol gap (OG) is commonly described by the formula [EtOH (mg/dL)]/k, where k is assumed to be 4.6 (one-tenth of its molecular weight) if ethanol behaves ideally in solution. However, several studies on convenience samples of patients suggest that ethanol does not behave ideally and that k may be significantly different from this ideal constant. OBJECTIVES: To determine prospectively the relationship between serum ethanol concentration and total serum osmolality in a group of healthy volunteers. METHODS: Experimental subjects ingested 20 mL of 100% ethanol diluted in sugar-free soda at a rate of one drink every 10 min, up to a maximum of seven drinks. Control subjects ingested 20 mL of water diluted in sugar-free soda at the same rate. Blood samples were obtained at baseline and then at every 20 min for 180 min to measure serum [EtOH] concentration, electrolytes, glucose, and osmolality (via freezing-point depression). The OG was calculated by subtracting predicted osmolality from measured osmolality. The OG was then divided by [EtOH] to determine the coefficient of ethanol's contribution to total serum osmolality. RESULTS: A total of 10 volunteers (five men and five women; mean age, 38.8 years, and range, 28-49 years) participated in and completed the study. Eight (four male and four female) were in the experimental group, and two (one male and one female) were in the control group. Mean peak [EtOH] was 229 mg/dL (median, 223.5 mg/dL; IQR, 171-273 mg/dL) and a linear relationship between [EtOH] and OG (Pearson coefficient of 0.98) was found. Using covariate correction for each subject's baseline OG, k was calculated to be 4.25 (95% CI, 4.13-4.38) averaged over all participants. CONCLUSIONS: In this volunteer study, the coefficient describing the contribution of ethanol to serum osmolality (k) was found to be 4.25. This indicates that ethanol contributes more to total serum osmolality than would be predicted for an ideal solute.

The kinetics of cell-substratum detachment mediated by trypsin: a comparison of normal and Duchenne fibroblasts.

In previous studies of cell-cell and cell-substratum adhesion, we have identified differences in the behaviour between human skin fibroblasts cultured from normal individuals and patients with Duchenne muscular dystrophy (DMD). In these studies, monolayer cultures were dissociated by trypsinization and no detectable difference was noted in the efficiency of cell dissociation between normal and DMD fibroblast cultures. However, a detailed study by Kent has suggested that Duchenne fibroblasts exhibit increased sensitivity to trypsin. We have re-investigated this finding using an assay that directly measures the number of cells remaining attached to a substratum following trypsinization. In a series of experiments using cultures derived from five normal and five DMD individuals, we can detect no significant difference in the trypsin-induced detachment rates between normal and DMD skin fibroblasts. This observation applies to both growth-phase and stationary-phase cell cultures. This inconsistency with previously reported data on the trypsin-sensitivity of DMD cells is considered in terms of the different assays used and the effects of trypsin on cell-cell and cell-substratum adhesion. The relationship between abnormalities in the behaviour of DMD cells and the localization and primary structure of the DMD gene product are also discussed.

Establishment of long-term myogenic cultures from patients with Duchenne muscular dystrophy by retroviral transduction of a temperature-sensitive SV40 large T antigen.

We have established long-term human myogenic cultures from adult human skeletal muscle biopsies by infecting primary explant cultures with an amphotropic retroviral construct encoding a temperature-sensitive SV40 large T antigen, tsA58-U19. Infected myoblasts expressed the large T antigen and showed greatly enhanced proliferative capacity when cultured at 33 degrees C, compared with noninfected cells. When the infected cultures were incubated at 39 degrees C, the cells withdrew from cycle, aligned, and fused to form multinucleated myotubes which expressed certain antigens that are similarly expressed in nontransduced differentiating muscle cells. Myogenic clones with greatly increased proliferative capacity were generated, for the first time, from biopsies obtained from Duchenne muscular dystrophy patients as well as from normal, dystrophin-positive individuals. Cell lines produced by this approach may prove valuable for in vitro studies of myogenesis and for investigating the cellular and molecular consequences of inherited muscle diseases.