Tissue engineering of arteries by directed remodeling of intact arterial segments

Traditional approaches to generating tissue-engineered arteries in vitro rely on expansion of cells in culture to seed appropriate scaffolds. In most envisioned applications, small autologous blood vessels would be harvested and used as a source for these cells. We propose that small autologous arteries, not the cells derived from them, may be an attractive starting point for engineered arteries. This approach capitalizes on the ability of intact arteries to grow and remodel in response to chronic changes in their mechanical environment. Carotid arteries from juvenile (approximately 30-kg) pigs were stretched longitudinally in an ex vivo perfusion system over 9 days. This resulted in a 40% increase in artery length at physiological longitudinal stress and a 20 +/- 3% increase when unstressed. Control arteries were perfused for 9 days ex vivo at their physiological loaded length. Control and elongated arteries displayed native appearance (macroscopic and histological), excellent viability (cellularity and mitochondrial activity), normal vasoactivity, and similar mechanical properties (ultimate stress and ultimate strain) as compared with freshly harvested arteries. Growth, as opposed to just redistribution of existing mass, contributed to elongation as evidenced by an increase in artery weight. Results on elongation of arteries from neonatal and adolescent pigs are also presented and discussed.     

Differential effects of growth factors on tissue-engineered cartilage

The effects of four regulatory factors on tissue-engineered cartilage were examined with specific focus on the ability to increase construct growth rate and concentrations of glycosaminoglycans (GAG) and collagen, the major extracellular matrix (ECM) components. Bovine calf articular chondrocytes were seeded onto biodegradable polyglycolic acid (PGA) scaffolds and cultured in medium with or without supplemental insulin-like growth factor (IGF-I), interleukin-4 (IL-4), transforming growth factor-beta1 (TGF-beta1) or platelet-derived growth factor (PDGF). IGF-I, IL-4, and TGF-beta1 increased construct wet weights by 1.5-2.9-fold over 4 weeks of culture and increased amounts of cartilaginous ECM components. IGF-I (10-300 ng/mL) maintained wet weight fractions of GAG in constructs seeded at high cell density and increased by up to fivefold GAG fractions in constructs seeded at lower cell density. TGF-beta1 (30 ng/mL) increased wet weight fractions of total collagen by up to 1.4-fold while maintaining a high fraction of type II collagen (79 plus minus 11% of the total collagen). IL-4 (1-100 ng/mL) minimized the thickness of the GAG-depleted region at the construct surfaces. PDGF (1-100 ng/mL) decreased construct growth rate and ECM fractions. Different regulatory factors thus elicit significantly different chondrogenic responses and can be used to selectively control the growth rate and improve the composition of engineered cartilage.     

Transmission of human immunodeficiency virus in a dental practice.

OBJECTIVE: To determine if patients of a dentist with the acquired immunodeficiency syndrome (AIDS) became infected with human immunodeficiency virus (HIV) during their dental care and, if so, to identify possible mechanisms of transmission. DESIGN: Retrospective epidemiologic follow-up of the dentist, his office practice, and his former patients. SETTING: The practice of a dentist with AIDS in Florida. PARTICIPANTS: A dentist with AIDS, his health care providers and employees, and former patients of the dentist, including eight HIV-infected patients. MEASUREMENTS: Identification of risks for HIV transmission (if present), degree of genetic relatedness of the viruses, and identification of infection control and other office practices. RESULTS: Five of the eight HIV-infected patients had no confirmed exposures to HIV other than the dental practice and were infected with HIV strains that were closely related to those of the dentist. Each of the five had invasive dental procedures, done by the dentist after he was diagnosed with AIDS. Four of these five patients shared visit days (P greater than 0.2). Breaches in infection control and other dental office practices to explain these transmissions could not be identified. CONCLUSION: Although the specific incident that resulted in HIV transmission to these patients remains uncertain, the epidemiologic evidence supports direct dentist-to-patient transmission rather than a patient-to-patient route.     

The future of proteomics in the study of alcoholism

This article represents the proceedings of a workshop at the 2003 annual meeting of the Research Society on Alcoholism in Fort Lauderdale, FL. The workshop organizers/chairpersons were Chinnaswamy Kasinathan and Paul Manowitz. The presentations were (1) Introduction to the field of proteomics, by Kent Vrana; (2) Use of proteomics in the identification of urinary biomarkers for alcohol intake, by Chinnaswamy Kasinathan, Paul Thomas, and Paul Manowitz; (3) Proteomics screening illuminates ethanol-mediated induction of HDL proteins in macaques, by Kent Vrana, Randy Gooch, Travis Worst, Stephen Walker, Aaron Xu, Peter Pierre, Heather Green, and Kathleen Grant; and (4) Proteomics applied to the study of the liver, by Laura Beretta.     

Diagnosis of tricuspid regurgitation. Current status

The most accepted diagnostic methods of tricuspid regurgitation (TR) are the physical examinations and the evaluation of right atrial pressure. However, these methods are not consistently diagnostic, and a "silent" form of TR has been recognized. The current status of noninvasive and invasive diagnostic techniques is reviewed.