Rapid skin permeabilization by the simultaneous application of dual-frequency, high-intensity ultrasound

Low-frequency ultrasound has been studied extensively due to its ability to enhance skin permeability. In spite of this effort, improvements in enhancing the efficacy of transdermal ultrasound treatments have been limited. Currently, when greater skin permeability is desired at a given frequency, one is limited to increasing the intensity or the duration of the ultrasound treatment, which carries the risk of thermal side effects. Therefore, the ability to increase skin permeability without increasing ultrasound intensity or treatment time would represent a significant and desirable outcome. Here, we hypothesize that the simultaneous application of two distinct ultrasound frequencies, in the range of 20 kHz to 3 MHz, can enhance the efficacy of ultrasound exposure. Aluminum foil pitting experiments showed a significant increase in cavitational activity when two frequencies were applied instead of just one low frequency. Additionally, in vitro tests with porcine skin indicated that the permeability and resulting formation of localized transport regions are greatly enhanced when two frequencies (low and high) are used simultaneously. These results were corroborated with glucose (180 Da) and inulin (5000 Da) transdermal flux experiments, which showed greater permeant delivery both into and through the dual-frequency pre-treated skin.

Rapid skin permeabilization by the simultaneous application of dual-frequency, high-intensity ultrasound

Low-frequency ultrasound has been studied extensively due to its ability to enhance skin permeability. In spite of this effort, improvements in enhancing the efficacy of transdermal ultrasound treatments have been limited. Currently, when greater skin permeability is desired at a given frequency, one is limited to increasing the intensity or the duration of the ultrasound treatment, which carries the risk of thermal side effects. Therefore, the ability to increase skin permeability without increasing ultrasound intensity or treatment time would represent a significant and desirable outcome. Here, we hypothesize that the simultaneous application of two distinct ultrasound frequencies, in the range of 20 kHz to 3 MHz, can enhance the efficacy of ultrasound exposure. Aluminum foil pitting experiments showed a significant increase in cavitational activity when two frequencies were applied instead of just one low frequency. Additionally, in vitro tests with porcine skin indicated that the permeability and resulting formation of localized transport regions are greatly enhanced when two frequencies (low and high) are used simultaneously. These results were corroborated with glucose (180 Da) and inulin (5000 Da) transdermal flux experiments, which showed greater permeant delivery both into and through the dual-frequency pre-treated skin.

Effect of computer support on younger women with breast cancer

OBJECTIVE

Assess impact of a computer-based patient support system on quality of life in younger women with breast cancer, with particular emphasis on assisting the underserved.

DESIGN

Randomized controlled trial conducted between 1995 and 1998.

SETTING

Five sites: two teaching hospitals (Madison, Wis, and Chicago, Ill), two nonteaching hospitals (Chicago), and a cancer resource center (Indianapolis, Ill). The latter three sites treat many underserved patients.

PARTICIPANTS

Newly diagnosed breast cancer patients (N = 246) under age 60.

INTERVENTIONS

Experimental group received Comprehensive Health Enhancement Support System (CHESS), a home-based computer system providing information, decision-making, and emotional support.

MEASUREMENTS AND MAIN RESULTS

Pretest and two post-test surveys (at two- and five-month follow-up) measured aspects of participation in care, social/information support, and quality of life. At two-month follow-up, the CHESS group was significantly more competent at seeking information, more comfortable participating in care, and had greater confidence in doctor(s). At five-month follow-up, the CHESS group had significantly better social support and also greater information competence. In addition, experimental assignment interacted with several indicators of medical underservice (race, education, and lack of insurance), such that CHESS benefits were greater for the disadvantaged than the advantaged group.

CONCLUSIONS

Computer-based patient support systems such as CHESS may benefit patients by providing information and social support, and increasing their participation in health care. These benefits may be largest for currently underserved populations.

Arabidopsis seed coat development: morphological differentiation of the outer integument

A morphological description of the differentiation of the outer integument of the Arabidopsis thaliana seed is presented. The period covered starts at about the octant embryo stage, extends to the mature seed, and concludes beyond that at the initial stages of seed imbibition. During this period the two-cell-layered outer integument goes through a dramatic differentiation process. The outer cell layer secretes mucilage in a ring between the plasma membrane and the outer cell wall at the corners of the cell. This secretion forces the cytoplasm into a columnar shape in the center of the cell. Before and during this process, starch granules are produced, initially at the center of the outer wall and later within the column. Late in differentiation, the starch granules are degraded as the cell produces a highly reinforced wall surrounding the columnar protoplast and at the radial walls between adjacent cells. This results in a cell containing large amounts of mucilage surrounding and completely outside of a highly reinforced columella. The mucilage and outer wall then dehydrate to leave the columella and radial walls visible as the epidermal plateau and reticulations visible on the mature seed. The inner cell layer of the outer integument also produces and degrades starch granules concomitantly with the outer layer but produces no mucilage. In the mature dry seed the collapsed outer wall remains connected to the top of the columella and the radial walls, but these connections are rapidly broken as the mucilage fully hydrates.

Demonstrating the added value of community health nursing for clients with insulin-dependent diabetes

The importance of demonstrating that nursing care adds value to client outcomes is discussed broadly as well as within the dimensions of a community health nursing outcomes study. The study examined the effect of a community health nursing intervention on the health behaviors and health status of adults with insulin-treated diabetes as measured by client outcomes using a two-group repeated measures experimental design. The findings indicate that the community health nursing intervention significantly enhanced the self-reported self-care behaviors of blood glucose testing, complication management, nutrition regimen adherence, and reporting foot change in the experimental group. No differences were found between the groups in outcomes for dietary adherence, foot care, blood glucose levels and overall diabetes knowledge, metabolic control, or functional health status. Challenges for community health nurse researchers engaging in client outcome studies are delineated and discussed.

Display of beta-lactamase on the Escherichia coli surface: outer membrane phenotypes conferred by Lpp'-OmpA'-beta-lactamase fusions

Bacterial cell-surface exposure of foreign peptides and soluble proteins has been achieved recently by employing a fusion protein methodology. An Lpp'-OmpA(46-159)-Bla fusion protein has been shown previously to display the normally periplasmic enzyme beta-lactamase (Bla) on the cell surface of the Gram-negative bacterium Escherichia coli. Here, we have investigated the role of the OmpA domain of the tripartite fusion protein in the surface display of the passenger domain (Bla) and have characterized the effects of the fusion proteins on the integrity and permeability of the outer membrane. We show that in addition to OmpA(46-159), a second OmpA segment, consisting of amino acids 46-66, can also mediate the display of Bla on the cell surface. Other OmpA domains of various lengths (amino acids 46-84, 46-109, 46-128, 46-141 and 46-145) either anchored the Bla domain on the periplasmic face of the outer membrane or caused a major disruption of the outer membrane, allowing the penetration of antibodies into the cell. Detergent and antibiotic sensitivity and periplasmic leakage assays showed that changes in the permeability of the outer membrane are an unavoidable consequence of displaying a large periplasmic protein on the surface of E. coli. This is the first systematic report on the effects that cell surface engineering may have on the integrity and permeability properties of bacterial outer membranes.

Influence of lung volume and alveolar pressure on reverse pulmonary venous blood flow

We have reported that left atrial blood refluxes through the pulmonary veins to gas-exchanging tissue after pulmonary artery ligation. This reverse pulmonary venous flow (Qrpv) was observed only when lung volume was changed by ventilation. This was believed to drive Qrpv by alternately distending and compressing the alveolar and extra-alveolar vessels. Because lung and pulmonary vascular compliances change with lung volume, we studied the effect of positive end-expiratory pressure (PEEP) on the magnitude of Qrpv during constant-volume ventilation. In prone anesthetized goats (n = 8), using the right lung to maintain normal blood gases, we ligated the pulmonary and bronchial arterial inflow to the left lung and ventilated each lung separately. A solution of SF6, an inert gas, was infused into the left atrium. SF6 clearance from the left lung was determined by the Fick principle at 0, 5, 10, and 15 and again at 0 cmH2O PEEP and was used to measure Qrpv. Left atrial pressure remained nearly constant at 20 cmH2O because the increasing levels of PEEP were applied to the left lung only. Qrpv was three- to fourfold greater at 10 and 15 than at 0 cmH2O PEEP. At these higher levels of PEEP, there were greater excursions in alveolar pressure for the same ventilatory volume. We believe that larger excursions in transpulmonary pressure during tidal ventilation at higher levels of PEEP, which compressed alveolar vessels, resulted in the reflux of greater volumes of left atrial blood, through relatively noncompliant extra-alveolar veins into alveolar corner vessels, and more compliant extra-alveolar arteries.

Influence of lung volume and left atrial pressure on reverse pulmonary venous blood flow

Infarction of the lung is uncommon even when both the pulmonary and the bronchial blood supplies are interrupted. We studied the possibility that a tidal reverse pulmonary venous flow is driven by the alternating distension and compression of alveolar and extra-alveolar vessels with the lung volume changes of breathing and also that a pulsatile reverse flow is caused by left atrial pressure transients. We infused SF6, a relatively insoluble inert gas, into the left atrium of anesthetized goats in which we had interrupted the left pulmonary artery and the bronchial circulation. SF6 was measured in the left lung exhalate as a reflection of the reverse pulmonary venous flow. No SF6 was exhaled when the pulmonary veins were occluded. SF6 was exhaled in increasing amounts as left atrial pressure, tidal volume, and ventilatory rates rose during mechanical ventilation. SF6 was not excreted when we increased left atrial pressure transients by causing mitral insufficiency in the absence of lung volume changes (continuous flow ventilation). Markers injected into the left atrial blood reached the alveolar capillaries. We conclude that reverse pulmonary venous flow is driven by tidal ventilation but not by left atrial pressure transients. It reaches the alveoli and could nourish the alveolar tissues when there is no inflow of arterial blood.

Measurement of right atrial oxygen saturation by fiberoptic oximetry accurately reflects mixed venous oxygen saturation in swine

Continuous fiberoptic measurement of mixed venous oxygen saturation (SvO2) via a pulmonary artery catheter is a useful, though invasive, monitoring technique. Continuous right atrial venous oxygen saturation measurement by oximetry offers the potential of a significantly less invasive SvO2 measurement. However, catheter motion, character of the vessel, chamber wall reflection, the filtering technique involved in calculating oxygen saturation, and the streaming of venous blood prior to ventricular mixing may influence the feasibility of continuous right atrial (RA) SvO2 measurement. This study investigated the performance of fiberoptically measured RA SvO2, at a position 2 cm from the tricuspid valve, relative to simultaneously measured pulmonary artery (PA) SvO2. Ten pigs were subjected to circulatory shock or chemically induced lung damage. Over a total monitoring period of approximately 40 hours, 464 paired data points were sampled at 5-minute intervals. The difference between the overall means of RA and PA SvO2 was 0.91% with a standard error of the estimate of 4.7%, a regression equation of RA SvO2 = PA SvO2 (0.94 + 2.1) PA So2, and a correlation coefficient of 0.94. Our conclusion, although extrapolated from a pig model, is that fiberoptic SvO2 monitoring may be accomplished less invasively and at a lower cost with a right atrial catheter.

Influence of G-suit abdominal bladder inflation on gas exchange during +GZ stress

Available data relating duration of +GZ stress to blood gas exchange status is limited. Furthermore, studies focusing on pulmonary gas exchange during +GZ stress when abdominal restriction is imposed have yielded conflicting results. To examine the time course of blood gas changes occurring during exposure to +GZ stress in dogs and the influence of G-suit abdominal bladder inflation on this time course, seven spontaneously breathing pentobarbital-anesthetized adult mongrel dogs were exposed to 60 s of up to +5 GZ stress with and without G-suit abdominal bladder inflation. Arterial and mixed venous blood were sampled for blood gas analysis during the first and last 20 s of the exposure and at 3 min postexposure. Little change in blood gas status was seen at +3 GZ regardless of G-suit status. However, with G-suit inflation, arterial PO2 fell by a mean of 14.7 Torr during the first 20 s at +4 Gz (P less than 0.01, t test) and 20.6 Torr at +5 GZ (P less than 0.01). It continued to fall an additional 10 Torr during the next 40 s at both +4 and +5 GZ. Arterial PO2 was still 5-10 Torr below control values (P less than 0.05) 3 min postexposure. A second series of experiments paralleling the first focused on blood gas status during repeated exposure to acceleration. Blood gas status was assessed in five dogs during the late 20 s of two 60-s exposures separated by 3 min at 0 GZ. No significant differences between the initial and repeated exposures were detected. The data indicate that G-suit abdominal bladder inflation promotes increased venous admixture.