The emerging role of contrast agents in echocardiography.

Because of an outstanding track record for diagnostic accuracy, noninvasive properties, ease of use, and relatively low expense, echocardiography has become a leading technique in the evaluation of cardiac disorders. In the three decades since echocardiography entered the ranks of standard cardiac diagnostic tools, refinements and technological advances have progressively increased its usefulness. One of the most noteworthy advancements has been the development of ultrasound contrast agents, which investigators are avidly seeking to apply to a broad spectrum of clinical settings and issues.

Effect of managed care on cardiovascular specialists: involvement, attitudes and practice adaptations.

Objectives: This study was undertaken to determine the extent to which cardiovascular specialists are involved with and affected by managed care and to ascertain their attitudes toward it. This survey also served as the follow-up to an initial study on the subject performed by the American College of Cardiology in 1993.

Background: The initial 1993 study was performed to address the lack of any comprehensive examination of the impact of managed care on cardiovascular specialists.

Cell biology of the primitive eukaryote Giardia lamblia.

Giardia lamblia is an extremely primitive or early-diverging eukaryote that has been considered to have no typical ER or Golgi apparatus, although it is a complex and highly developed cell. Both the trophozoite and cyst have unusual surface proteins that enable these stages to survive in very different and hostile environments. We found that G.

A lipoprotein-cholesterol-albumin serum substitute stimulates Giardia lamblia encystation vesicle formation.

We found previously that the A6 clone of Giardia lamblia strain WB that did not encyst in vitro was blocked at an early stage in differentiation, as it did not form encystation secretory vesicles (ESV) efficiently or express cyst antigens, in comparison with the related clone C6. We now report that A6 formed ESV normally in the suckling mouse model. Therefore, we asked whether our serum-containing encystation media might lack a stimulus or component or contain an inhibitor of ESV formation to which A6 was especially sensitive.

Racial differences in epinephrine and beta 2-adrenergic receptors.

This study examined the effects of ethnicity and hypertension on beta 2-adrenergic receptors and on plasma catecholamines in a group of 77 unmedicated mildly hypertensive and normotensive men. Black hypertensive subjects had the most sensitive and white hypertensive subjects the least sensitive beta-receptors (as assessed by isoproterenol-stimulated cyclic AMP in lymphocytes [P = .02]).

Perfluorocarbon-enhanced sonography: value in detecting acute venous thrombosis in rabbits.

Objective: We have previously shown that perfluorocarbon emulsions administered i.v. act as contrast material during sonography by creating moving echoes in veins.

Pregnancy, lactation and the use of silicone breast implants.

In the United States alone, an estimated 1-2 million women have used silicone breast implants. Many of these women are of reproductive age. Given the current controversy over the safety of silicone breast implants, medical care providers should be able to advise women if use of these implants affects the use of any of the available contraceptive methods, whether pregnancy is in any way contraindicated and/or might be associated with special complications, whether there are potential risks to the fetus and neonate, and whether breast feeding might be compromised.

Development of anti-tumor immunity following thymidine kinase-mediated killing of experimental brain tumors.

Using the 9L experimental brain tumor model, we studied long-term tumor regression and immunologic consequences of tumor killing in a model of in vivo gene transfer of the herpes simplex virus 1 thymidine kinase (HSV-TK) gene and ganciclovir (GCV) treatments. Fibroblasts modified to produce retroviral vectors carrying the HSV-TK gene were implanted into established 9L brain tumors in Fischer 344 rats to carry out gene transfer. Animals were then treated with parenteral GCV.

Managed care involvement by cardiovascular specialists: prevalence, attitudes and influence on practice.

Objectives: The purpose of this study was to determine the involvement in and attitudes toward managed care by cardiovascular specialists and the influence of such programs on their practices.

Background: No in-depth study has measured the impact of managed care on cardiovascular specialists. Therefore, we conducted a mail survey to determine the prevalence of managed care arrangements among cardiovascular specialists and variations among pediatric and adult cardiologists and cardiovascular surgeons; the types of managed care arrangements in which cardiovascular specialists are engaged; the reasons why those not participating in managed care have chosen not to do so; and the general attitudes among cardiovascular specialists with regard to various aspects of managed care.

Reperfusion injury and exhaled hydrogen peroxide.

Reactive oxygen species have been implicated in the pathophysiology of lung injury associated with the sequence of ischemia-reperfusion. To study this, we measured the exhaled breath hydrogen peroxide concentration [H2O2] in human and canine models of reperfusion lung injury. Our models were patients subjected to cardiopulmonary bypass (CPB) (Group 1), patients undergoing pulmonary thromboendarterectomy (Group 2), canine single lung transplant (Group 3), and patients subjected to peripheral ischemia resulting from aortic cross-clamping or tourniquet application (Group 4).

Development of a novel spontaneous metastasis model of human osteosarcoma transplanted orthotopically into bone of athymic mice.

There is a pressing need for in vivo models in which potential antitumor agents can be tested for their ability to inhibit the growth and metastatic spread of human sarcomas. A recent advance in this regard has been the development of a v-Ki-ras-oncogene-transformed human osteosarcoma cell line (KRIB) that efficiently colonizes the lungs of athymic nude mice when cells (1 x 10(5)) are administered by i.v.

Mechanisms of tissue destruction and cellular activation in rheumatoid arthritis.

Rheumatoid arthritis is a chronic inflammatory disease of unknown etiology that is marked by synovial inflammation and destruction of articular extracellular matrix. Several studies of the pathogenesis of tissue destruction have focused on the production of metalloproteinases and their inhibitors in synovium as determinants of joint preservation. Also, the role of cytokines in the perpetuation of synovitis and of superantigens in synovial T-cell activation have led to novel hypotheses that attempt to explain abnormalities of synovial structure and function in rheumatoid arthritis.

Breast implants under siege: an historical commentary.

Despite 3 decades of rapidly expanding application of polydimethylsiloxane as a relatively safe implantable biomaterial, the American public is being told by a vocal minority that its use in the breast implant may be dangerous. Most of the furor has been generated by consumer advocates with support of a handful of scientists who have expressed opinions, not well supported by facts, about the risks of these devices. These anxieties have been fueled in the public's mind by a media more interested in sensationalism than disciplined reporting.