Relationship between esophageal muscle thickness and intraluminal pressure: an ultrasonographic study

A number of studies show a close temporal relationship between the rate of change in muscle thickness as detected by high-frequency intraluminal ultrasonography (HFIUS) and intraluminal pressure measured by manometry. There is a marked variability in esophageal contraction amplitude from one swallow to another at a given level in the esophagus and along the length of the esophagus. Furthermore, peristaltic pressures are higher in the distal compared with the proximal esophagus. The goal of this study was to evaluate the relationship between the baseline and peak muscle thickness and the contraction amplitude during swallow-induced contractions along the length of the esophagus. Fifteen normal subjects were studied using simultaneous esophageal pressures and HFIUS or HFIUS alone. Recordings were made during baseline and standardized swallows in the lower esophageal sphincter (LES) and at 2, 4, 6, 8, and 10 cm above the LES. HFIUS images were digitized, and esophageal muscle thickness and peak contraction amplitudes were measured. In the resting state, muscle thickness is higher in the LES compared with the rest of the esophagus. Baseline muscle thickness is also significantly higher at 2 cm vs. 10 cm above the LES. In a given subject and among different subjects, there is a good relationship between peak muscle thickness and peak peristaltic pressures (r = 0.55) at all sites along the length of the esophagus. The positive correlation between pressure and muscle thickness implies that the mean circumferential wall stress is fairly uniform from one swallow to another, irrespective of the contraction amplitude.     

In search of the ideal female umbilicus

The umbilicus is essential to the aesthetic appearance of the abdomen. However, little research exists on what characterizes an aesthetically pleasing umbilicus. Often, the plastic surgeon is called on to reconstruct the umbilicus. Although a variety of reconstructive methods are available, no real standards define the appearance of an aesthetically pleasing umbilicus. To ascertain the characteristics of an aesthetically pleasing umbilicus, a photographic analysis was undertaken using 147 female participants between the ages of 18 and 62 years. Each subject's age, height, and weight were recorded. Photographs of each participant's umbilicus were then taken from 30 cm and 50 cm away. The photographs were reviewed by the authors, and each umbilicus was categorized on the basis of size, shape, hooding, or protrusion. The photographs were then reviewed by a panel and given a score between 1 and 10 to rate attractiveness. Using linear regression analysis, the effects of body mass index, shape, hooding, and umbilical protrusion on attractiveness were assessed. The T- or vertically shaped umbilicus with superior hooding consistently scored the highest in aesthetic appeal, whereas the presence of any degree of protrusion and a horizontal orientation or distorted shape detracted from the score. Those with a large umbilicus tended to score consistently lower than those with a smaller configuration. A desirable goal in umbilical reconstruction is, thus, to create a small T or vertically oriented umbilicus with the addition of a superior hood or shelf.     

Ultrasound system to measure esophageal varix pressure: an in vitro validation study

We report our experience with an ultrasound system to measure esophageal varix pressure in an in vitro model. The ultrasound system consists of a 12.5 MHz frequency intraluminal ultrasound probe, a water infusion catheter, and a manometry catheter, all contained within a nondistensible latex bag. Esophagi and external jugular veins were harvested from five pigs. The vein and ultrasound system were placed inside the esophagus. One end of the vein was connected to a water reservoir to modulate its pressure; the other end was connected in two different ways to simulate hydrodynamic and hydrostatic flow conditions. The bag was inflated with water until vein occlusion was discernible on the ultrasound images. The influences of vein pressure, vein cross-sectional area and esophageal elasticity on the ultrasound measurement of vein pressure were assessed. A total of 108 trials were performed at nine different vein pressures. Complete vein occlusion occurred when the bag pressure was slightly greater (1.4 +/- 0.7 mmHg) than the vein pressure. For a vein pressure of 25 mmHg, the average occlusion and opening pressures were 27 +/- 0.2 and 25.7 +/- 0.3 mmHg, respectively (P < .05) suggesting that the vein opening pressure on the ultrasound images is more accurate than the vein closing pressure. In conclusion, the ultrasound technique can accurately measure intravariceal pressure in vitro. The bag pressure at the point of vein reopening is the best determinant of the vein pressure.     

Mechanism of cellular uptake of a ruthenium polypyridyl complex

Transition metal complexes provide a promising avenue for the design of therapeutic and diagnostic agents, but the limited understanding of their cellular uptake is a roadblock to their effective application. Here, we examine the mechanism of cellular entry of a luminescent ruthenium(II) polypyridyl complex, Ru(DIP) 2dppz (2+) (where DIP = 4,7-diphenyl-1,10-phenanthroline and dppz = dipyridophenazine), into HeLa cells, with the extent of uptake measured by flow cytometry. No diminution of cellular uptake is observed under metabolic inhibition with deoxyglucose and oligomycin, indicating an energy-independent mode of entry. The presence of organic cation transporter inhibitors also does not significantly alter uptake. However, the cellular internalization of Ru(DIP) 2dppz (2+) is sensitive to the membrane potential. Uptake decreases when cells are depolarized with high potassium buffer and increases when cells are hyperpolarized with valinomycin. These results support passive diffusion of Ru(DIP) 2dppz (2+) into the cell.