Vincent J. Caiozzo
Associate Adjunct Professor, Orthopaedic Surgery
School of Medicine
PH.D., University of California, Irvine
Phone: (949) 824-5571
Fax: (949) 824-8540
University of California, Irvine
B152 Medical Sciences 1
Mail Code: 5399
Irvine, CA 92697
Skeletal muscle adaptation, sarcomeric proteins, contractile properties, rehabilitation
My current research interests are focused on 3 key aspects of skeletal muscle: i) the mechanistic role of contractile and regulatory proteins in muscle mechanics; ii) the mechanistic basis of muscle plasticity; and iii) the application of the first two pursuits to clinically relevant pathologies.
Regarding the first area, previous studies conducted in my laboratory have focused upon the relationship between myosin isoforms and maximal shortening velocity. Current studies are directed at a more complete understanding of the role of myosin using whole muscle, single motor unit, and single fiber studies. Using the novel work loop technique, I have been able to develop a model that describes the role of activation and relaxation processes in limiting the mechanical work produced by skeletal muscle during repetitive contractions. These studies have shown that relaxation plays a major role in limiting the amount of mechanical work that can be produced by skeletal muscle, and that relaxation is length and strain dependent. Future studies with single fibers will specifically focus upon the role of myosin, troponin-C , and the sarcoplasmic reticulum in the relaxation process by using caged chelators of calcium that are activated by laser flash photolysis.
From a clinical perspective, the Ilizarov technique is used to lengthen long bones and salvaging limb length following traumatic injuries. While previous studies have exclusively focused upon issues related to bone, very little is known about the response of skeletal muscle, connective tissue, nerve, or vessels to distraction. The ability to lengthen bone using the Ilizarov technique is thought to be limited by the soft tissues adjacent to the bone defect. As a result of constant bone lengthening, skeletal muscles are also under constant stretch. Currently, it is not known what effect bone lengthening has on the contractile, biochemical, and molecular properties of skeletal muscle. As a result, we have developed a rodent Ilizarov model that simulates that used in humans. Our current interests are to examine the adaptability of the flexors and extensors of a joint to constant stretch. By developing an understanding of the adaptation of skeletal muscle to the Ilizarov technique, more optimal methods of bone lengthening should be developed.
Wu, Y.Z., R.L. Crumley, R.H. Blanks, and V.J. Caiozzo. Are hybrid fibers a common motif of canine laryngeal muscles: single fiber analyses of myosin heavy chain isoform composition. Arch. Otolaryn. 126:865-873, 2000
Wu, Y.Z., R.L. Crumley, and V.J. Caiozzo. New perspectives on human laryngeal muscle: single fiber analyses and interspecies comparisons. Arch. Otolaryn. 126:857-864, 2000
Wu. Y.Z., M.J. Baker, R.L. Crumley, and V.J. Caiozzo. Single fiber MyHC isoform composition of rodent laryngeal muscle: modulation by thyroid hormone. Arch. Otolaryn. 126:874-880, 2000
DiMaso, N., V.J. Caiozzo, K.M. Baldwin. Single fiber myosin heavy chain polymorphism during postnatal development: modulation by hypothyroidism. Am. J. Physiol. 278:R1099-R1106, 2000.
American Physiological Society