Gary L. Engelmann

Argon ion laser-excited autofluorescence in normal and atherosclerotic aorta and coronary arteries: morphologic studies.

Argon ion laser-excited autofluorescence was studied in unstained frozen sections of 47 normal and atherosclerotic human aortas and coronary arteries by means of a bright-field microscope modified for fluorescence microscopy with 476 nm argon ion laser epillumination, and compared to morphology in serial sections stained with H & E, Movat pentachrome, and oil red O. Normal artery autofluorescence correlated morphologically with the structural protein fibers elastin and collagen in the intima, media, and adventitia. Atherosclerotic plaque autofluorescence correlated morphologically with lipid or calcified deposits in the atheroma core. The autofluorescence of these deposits differed from that of elastin and collagen in distribution, intensity, and color, and increased with the severity of the plaque. We conclude that argon ion laser-excited autofluorescence in normal and atherosclerotic arteries correlates with morphology and has diagnostic potential in laser angiosurgery.

Transforming growth factor-beta1 in heart development

Abstract Defined biochemical stimuli regulating neonatal ventricular myocyte (cardiomyocyte) development have not been established. Since cardiomyocytes stop proliferating during the first 3–5 days of age in the rodent, locally generated ‘anti-proliferative’ and/or differentiation signals can be hypothesized. The transforming growth factor-beta (TGF-β) family of peptides are multifunctional regulators of proliferation and differentiation of many different cell types. We have determined in neonatal and maturing rat hearts that TGF- β 1 gene expression occurs in pups of both normotensive (Wistar Kyoto, WKY) and hypertrophy-prone rats (spontaneously hypertensive, SHR). TGF- β 1 transcript levels were readily apparent in total ventricular RNA from SHR pups within 1 day of age and elevated in 3–7 day old WKY and SHR hearts when cardiomyocyte proliferation indices are diminished. TGF- β 1 transcript levels remain at a ‘relatively’ high level throughout maturation and into adulthood in both strains. Further, TGF- β 1 transcripts were localized to cardiomyocytes of neonatal rat ventricular tissue sections by in situ hybridization. Immunoreactive TGF-β was co-localized to the intracellular compartment of neonatal cardiomyocytes at the light and electron microscopic level. In vitro analysis using primary cultures of fetal and neonatal cardiomyocytes indicated that TGF-βs inhibit mitogen stimulated DNA synthesis and thymidine incorporation. From these data, we propose that locally generated TGF-βs may act as autocrine and/or paracrine regulators of cardiomyocyte proliferation and differentiation as intrinsic components of a multifaceted biochemical regulatory process governing heart development.

Argon Ion Laser Induced Tissue Fluorescence: Clinical Spectroscopic Studies

In conjunction with our project in laser angiosurgery, our group has demonstrated that laser-induced auto-fluorescence can be a reliable means of distinguishing normal artery from atherosclerotic plaque. Recently a number of groups have become interested in this technique as a means of directing ablation of arterial obstructions in vivo. However, until now, diagnostic spectroscopy has been conducted almost solely on excised cadaveric tissues. As a result, questions still remain about 1) the validity of correlating cadaveric tissue fluorescence spectra with those collected in vivo, and 2) the ability to collect reliable florescence spectra from a subject as dynamic as a living patient.

Insulin-Like Growth Factors and Heart Development

Growth of the adult mammalian ventricular myocyte (cardiomyocyte) is the topic of considerable interest since heart muscle cells rapidly respond to increases in functional demands by an increase in cellular mass(l). Although the cardiomyocyte of the adult ventricle occupies up to 90% of the area of the left ventricle (LV) free wall, these cells comprise a unique population of a permanently post-mitotic, structurally and functionally delimited cell type that can only expand in width (primarily) and length to increasing functional demand on this vital organ. Therefore, the adult cardiomyocyte population is a static number of muscle cells that define the life-long structure and function of the ventricular portion of the heart. It is the function of the cardiomyocytes that can then be modulated by adjacent cell types (i.e., fibroblasts and endothelium), blood vessels (capillaries and arterioles) and neural/humoral stimuli in the mature organ.

Argon Ion Laser Angiosurgery In Different Animal Models Using A Multifiber Optical Delivery System

Stenotic or occlusive (two different techniques) lesions were surgically induced in the canine common carotid artery. The lesions were evaluated angiographically prior to as well as after laser angiosurgery (LAS). LAS was performed in 30 dogs using a continuous wave (CW) argon ion laser (Innova 20) coupled to a multifiber, quartz-shielded, fiberoptic catheter. Successful removal of lesion tissue was achieved in 89% of the animals with stenoses and in 40% and 82% in each of the two groups of dogs with occlusions. In the latter two groups, perforation of the vessel wall during LAS was encountered in 60% and 18%, respectively. No perforations occurred in the stenotic animals, where long-term follow-up was possible for up to 60 days with a patency rate of 63% and morphological evidence of excellent healing with complete reendothelialization.