Identifying the motivations of African American volunteers working to prevent HIV/AIDS.

Community-based organizations that are engaged in HIV/AIDS prevention and support services often rely on volunteers. This article describes the development of a 22-item inventory that measures the motivations of volunteers who deliver HIV prevention education in the African American community. In a statewide survey of volunteers (N = 102), the two strongest motivations for volunteer activity were concern for the African American community and a desire to understand the causes and consequences of the epidemic. These motives predicted the frequency that volunteers held discussions about HIV/AIDS with members of their community. Discussion focuses on the relevance of the results for the recruitment, training, and retention of volunteers.

What makes recovered-memory testimony compelling to jurors?

Little is known about how jurors arrive at verdicts in cases involving recovered memories of childhood sexual abuse. Study 1 investigated mock jurors' reactions to the recovered-memory testimony of an alleged victim when a therapist intervened with hypnosis, suggestion, or symptom management. When a therapist used hypnosis, jurors viewed the victim's recovered-memory testimony as particularly accurate and credible, and favored the victim in their verdicts. In Study 2, mock jurors were presented with a therapist who was sued for allegedly influencing a client's recall of false memories of abuse. In this case, however, jurors viewed therapists who used hypnosis or suggestion as more likely to have created false memories, more responsible for having caused harm, and less competent, and tended not to favor these therapists in their verdicts. We discuss these seemingly contradictory findings in terms of how culturally formed expectancies about hypnosis produce different causal explanations depending on the focus of a trial.

Among friends? An examination of friendship and the self-serving bias.

Do friends bound each other's self-enhancement tendencies? Do friends display the self-serving bias (SSB; i.e. taking individual credit for success but blaming a partner for failure)? Dyads consisting of either friends or strangers engaged in an interdependent-outcomes creativity test, received bogus success or failure feedback at the dyadic level, and made responsibility attributions for the joint test performance. Strangers displayed the SSB. Friends, in contrast, refrained from the SSB: they shared responsibility for both successful and unsuccessful test outcomes. Friendship does place boundaries on self-enhancement.

African-American volunteers carrying an HIV prevention message: selective communication.

Despite increased resources and funding, the rate of new HIV infections has not been contained within the African American community. Initiatives such as the culturally specific American Red Cross African American HIV/AIDS Program have enlisted thousands of volunteers in the fight against AIDS. This article reports the findings of a survey given to program volunteers, focusing on their prevention-related activities. The results suggest that although volunteers felt good about their level of knowledge and about their prevention work, they were selective both in terms of the audiences they addressed and in terms of the topics they covered. Specifically, volunteers were more likely to discuss HIV prevention with acquaintances than with their own family members or with a sexual partner. In addition, volunteers tended not to discuss the dangers of sharing needles.

Development of a low flow resistance intravenous oxygenator.

A potentially attractive support device for patients with acute respiratory failure is an intravenous membrane oxygenator. One problem, however, is that the membrane surface area required for sufficient gas exchange can unduly increase vena caval pressure drop and impede venous return. The purpose of this study was to design and develop an intravenous oxygenator that would offer minimal venous flow resistance in situ. The device uses a constrained fiber bundle of smaller cross sectional size than the vena cava so as to effect an intentional shunt flow of venous blood around the fiber bundle and reduce the venous pressure drop caused by the device. A pulsating balloon within the fiber bundle redirects part of this shunt flow into reciprocating flow in and out of the fiber bundle. This offers dual advantages: 1) Blood flow through the fiber bundle is mainly perpendicular to the fibers; and 2) the requisite energy for driving flow comes largely from the pneumatic system pulsating the balloon, not from a venous pressure drop. In this mode a full length device with a 2 cm fiber bundle in a 2.5 cm blood vessel would offer a pressure drop of only a few millimeters of mercury. The use of constrained fiber bundles requires good uniformity of fiber spacing for effective gas exchange. Several prototypes have been fabricated, and CO2 and O2 exchange rates of up to 402 and 347 ml/min/m2 have been achieved during acute animal implantation.

Activity and similarity on safe sex workshops led by peer educators.

OBJECTIVES: Sexually transmitted disease is a growing problem for college students. To address this problem, health professionals on many campuses have turned to peer led prevention workshops. The research evaluated the effectiveness of four types of such workshops. METHODS: The workshops followed either an information based format or an activity based format. In addition, the peer leaders were portrayed as similar to their audience or as dissimilar. RESULTS: Results indicate that the Activity Workshop was more effective than the Information Workshop at encouraging condom use in the month following the workshop. Also, the similarity of the peer leaders influenced behavioral intentions to use a condom with new sex partners. CONCLUSIONS: The discussion focuses on self-persuasion and changes in social norms as possible theoretical mechanisms underlying these effects.

Acute in vivo studies of the Pittsburgh intravenous membrane oxygenator.

The efficacy of an innovative intravenous membrane oxygenator (IMO) was tested acutely (6-8 hrs) in seven calves. The IMO prototypes consisted of a central polyurethane balloon within a bundle of hollow fibers with a membrane surface area of 0.14 m2. The IMO devices were inserted through the external jugular vein into the inferior vena cava of anesthetized calves (68.9 +/- 2.3 kg). Rhythmic balloon pulsation (60-120 bpm) was controlled with an intra-aortic balloon pump console. Oxygen sweep gas was delivered through the device at 3.0 L/min. Gas concentrations were monitored continuously by mass spectroscopy. The principal results were as follows: 1) oxygen and carbon dioxide exchange ranged from 125 to 150 ml/min/m2 and 150 to 200 ml/min/m2, respectively; 2) there was at least a 30-50% augmentation of gas exchange with balloon pulsation; 3) maximum exchange occurred with 60-90 bpm balloon pulsations; and 4) hemodynamic parameters remained unchanged. There were no device related complications, and the feasibility of insertion of the device by a cervical cut-down was established. These acute in vivo experiments show that the Pittsburgh IMO device can exchange oxygen and carbon dioxide gases in vivo at levels consistent with this current prototype design, and that intravenous balloon pulsation significantly enhances gas exchange without causing any end-organ damage.

Development of an intravenous membrane oxygenator: enhanced intravenous gas exchange through convective mixing of blood around hollow fiber membranes.

In vitro testing of a new prototype intravenous membrane oxygenator (IMO) is reported. The new IMO design consists of matted hollow fiber membranes arranged around a centrally positioned tripartite balloon. Short gas flow paths and consistent, reproducible fiber geometry after insertion of the device result in an augmented oxygen flux of up to 800% with balloon activation compared with the static mode (balloon off). Operation of the new IMO device with the balloon on versus the balloon off results in a 400% increase in carbon dioxide flux. Gas flow rates of up to 9.5 L/min through the 14-cm-long hollow fibers have been achieved with vacuum pressures of 250 mm Hg. Gas exchange efficiency for intravenous membrane oxygenators can be increased by emphasizing the following design features: short gas flow paths, consistent and reproducible fiber geometry, and most importantly, an active means of enhancing convective mixing of blood around the hollow fiber membranes.

Development of an intravenous membrane oxygenator: a new concept in mechanical support for the failing lung.

An intravenous membrane oxygenator is being developed to supplement oxygen and carbon dioxide exchange in patients with temporary and potentially reversible lung failure in either a lung transplantation setting or in cases of acute respiratory distress from multiple causes. Our device incorporates a pulsatile balloon that is centrally located and around which are mounted microporous hollow fibers. Oxygen is vaccuumed through the fibers with resultant gas exchange. The rhythmic pulsations of the balloon enhance cross-flow and three-dimensional convective mixing at the blood-fiber interface and thus promote more efficient oxygen-carbon dioxide exchange. Seven intravenous membrane oxygenator prototypes have been designed and fabricated. Modifications in design have led to a progressive improvement in gas flux. Gas exchange performance measured in vitro and with both saline solution and fresh ox blood have shown gas exchange as high as 203 ml/min/m2 for oxygen and 182 ml/min/m2 for carbon dioxide. In vivo dog experiments with the device positioned in the inferior vena cava and right atrium have shown over a 50% increase in oxygen flux with balloon activation versus the static situation without changes in hemodynamics. The size of the prototype tested in animals can be scaled up fivefold for anticipated human trials. Our results indicate that our intravenous membrane oxygenator prototypes now under development may be an alternative to extracorporeal membrane oxygenation in the treatment of temporary respiratory failure.

Vibration analysis of vessel wall motion with intra vena caval balloon pumping.

The intravenous membrane oxygenator (IMO) incorporates a centrally positioned balloon surrounded by hollow microporous fibers. Previous studies using this configuration have demonstrated that rhythmic pulsation of the balloon enhances gas exchange, presumably by three dimensional convective mixing. This study sought to characterize vessel wall vibrations imparted by intra vena caval balloon pumping. An in vitro flow loop incorporating a current IMO prototype was used for these measurements. The IMO prototype was inserted in a modeled vena cava on which ultrasonic dimension transducers were mounted on the outer surface. The flow loop was operated at physiologic flow rates. The balloon was activated, and dynamic vessel diameter measurements were recorded as the pumping frequency was varied from 40 to 120 beats per minute (bpm). A Fast Fourier Transform algorithm generated a frequency spectrum at each bpm and for two different balloon configurations; a single balloon versus a tripartite arrangement, the authors' results demonstrate that the mean amplitude of vena caval oscillations varied with bpm, and that this variation followed the trends in oxygen transfer rates. This suggests that the motion of the vessel wall may contribute to convective mixing of blood. In addition, this work demonstrated significant differences in the frequency spectra associated with our two balloon configurations.

In vitro analysis of shed blood from patients undergoing total knee replacement surgery.

One method used to obtain autologous blood includes collection of wound drainage postoperatively. The decision to wash wound drainage before infusion is left to individual institutions. The composition of blood collected from joint spaces has not been adequately evaluated. Wound drainage from total knee replacement was collected into a cardiotomy reservoir, without anticoagulation, for 4 hours after surgery. Coagulation parameters were evaluated on the washed supernatant and unwashed supernatant. The most significant findings were the following: 1. Modified prothrombin time: washed supernatant and unwashed supernatant were substituted for tissue thromboplastin reagent. The unwashed supernatant initiated fibrin formation (mean, 108 seconds), whereas the washed supernatant did not (mean, > 150 seconds, P = .01). 2. Euglobulin lysis times: Mixtures containing 50% normal plasma and 50% washed supernatant or unwashed supernatant were used to determine plasmin activation (unwashed supernatant + normal plasma = 24 minutes; washed supernatant + normal plasma = 106 minutes; P = .03). Lower euglobulin lysis times indicates increased plasmin activity. 3. Fibrin degradation products: Concentrations were significantly elevated in unwashed supernatant (mean 10,240 micrograms/mL) versus washed supernatant (mean 5 micrograms/mL, P = .02). Fibrin degradation products are inhibitors of fibrin formation and platelets. The authors conclude the unwashed supernatant from wound drainage collected after total knee replacement contains activated components of the soluble coagulation and fibrinolytic systems, and these substances can be significantly reduced with washing.

Current progress in the development of an intravenous membrane oxygenator.

In vitro testing of an intravenous membrane oxygenator (IMO) consisting of hollow fiber membranes arranged around a centrally positioned balloon is reported. A total of six IMO prototypes were mounted in a specially designed mock circulatory loop and perfused with physiologic saline or fresh abattoir ox blood to investigate their oxygen and carbon dioxide transfer capabilities. One IMO prototype was mounted in the flow loop and perfused with saline for 13 continuous days to test the durability and reliability of the prototype design. It is the authors' hypothesis that the rhythmic inflation and deflation of the balloon increases convective mixing and cross-flow of blood around the fibers, thereby enhancing gas exchange capabilities. The results of these trials support this contention, namely that gas exchange efficiency rose with increasing frequency of balloon pulsation. No significant deterioration in oxygen transfer was observed in the durability test prototype, which was continuously perfused with saline for 13 days.

Respiratory dialysis. A new concept in pulmonary support.

Use of a new intravenous oxygenator made of hollow fiber membranes arranged around a centrally positioned balloon is reported. In vitro studies using fluorescent image tracking velocimetry and gas exchange analysis demonstrated enhanced convective mixing with balloon pulsations and augmented gas flux (100% increase in pO2) compared with the device in its static configuration. In vivo observations confirmed a greater than 50% increase in O2 flux with balloon activation. Those parameters that produce radial flow and convective mixing in vitro enhance gas flux in vivo, thus confirming the efforts to exceed the fluid limit translate into improved gas exchange.