Yoann H. Millet

Tissue engineering and biomaterials in regenerative medicine.

The field of regenerative medicine offers the potential to significantly impact a wide spectrum of healthcare issues, from diabetes to cardiovascular disease. In particular, the design of tailored biomaterials, which possess properties desired for their particular application, and the development of superior implant environments, which seek to meet the nutritional needs of the tissue, have yielded promising tissue engineering prototypes. In this commentary, we examine the novel approaches researchers have made in customized biomaterials and promoting angiogenesis that have led to significant advancements in recent years.

Genetic and phenotypic studies of the dark-like mutant mouse

The dark‐like (dal) mutant mouse has a pleiotropic phenotype that includes dark dorsal hairs and reproductive degeneration. Their pigmentation phenotype is similar to Attractin (Atrn) mutants, which also develop vacuoles throughout the brain. In further characterizing the testicular degeneration of dal mutant males, we found that they had reduced serum testosterone and developed vacuoles in their testes. Genetic crosses placed dal upstream of the melanocortin 1 receptor (Mc1r) and downstream of agouti, although dal suppressed the effect of agouti on pigmentation but not body weight. Atrnmg‐3J and dal showed additive effects on pigmentation, testicular vacuolation, and spongiform neurodegeneration, but transgenic overexpression of Attractin‐like‐1 (Atrnl1), which compensates for loss of ATRN, did not rescue dal mutant phenotypes. Our results suggest dal and Atrn function in the same pathway and that identification of the dal gene will provide insight into molecular mechanisms of vacuolation in multiple cell types. genesis 46:562–573, 2008.

Body contouring after bariatric surgery: how much is really being done?

Abstract The proportion of postbariatric surgery patients who undergo body contouring (BC) procedures is unknown. We designed a study to explore demographic features and patient education regarding BC in the bariatric surgery (BS) population. A survey was mailed to 1158 patients who underwent BS by 2 surgeons between 2003 and 2011. A total of 284 (24.5%) patients responded. Seventy-two patients (25.4%) reported discussing BC surgery with their bariatric surgeon perioperatively. Forty patients (14.1%) were referred for plastic surgery consultation. Thirty-three patients (11.6%) underwent BC procedures. The most frequent reasons cited for not undergoing BC were expense (29.2%) and lack of awareness regarding options (23.6%). Thirty-nine percent of respondents reported that they might have chosen differently, had they received more information. As a result of insufficient perioperative counseling, the majority of BS patients are unaware of the multitude of BC procedures available. Additional efforts toward improving patient (and surgeon) education regarding postbariatric BC options are warranted.

Developmental cardiac hypertrophy in a mouse model of prolidase deficiency.

BACKGROUND Hypertrophic cardiomyopathy, characterized by thickened ventricular walls and reduced ventricular chamber volume, is a common cause of sudden cardiac death in young people. Most inherited forms result from mutations in genes encoding sarcomeric proteins. METHODS Histologic analysis identified embryonic cardiac hypertrophy in dark-like mutant mice. BrdU analysis was performed to measure proliferation and cardiomyocytes were isolated to measure cell size. The dark-like mutation was identified by positional cloning. RESULTS The dark-like mutation causes cardiomyocyte hypertrophy due to loss-of-function of peptidase d (Pepd), which encodes prolidase, a cytosolic enzyme that recycles proline for collagen re-synthesis. Prolidase deficiency is a rare autosomal recessive disease in humans with a broad phenotypic spectrum not reported to include heart defects, but a conserved role for prolidase in heart development was confirmed by morpholino knockdown in zebrafish. We tested the hypothesis that loss of prolidase function disrupts collagen-mediated integrin signaling and determined that the levels of several key integrin transducers were reduced in the hearts of dark-like mutant embryos. CONCLUSIONS This work identifies dark-like mice as a model of prolidase deficiency that will be valuable for studying the role of proline metabolism in normal physiology and disease processes, and suggests that integrin signaling may regulate the onset of hypertrophic cardiac growth.

7: SOLVING THE QUESTION OF PROTECTION: HYDROGEN SULFIDE CONFERS PROTECTION FROM IRI VIA ACTIVATION OF THE JAK-STAT PATHWAY

Introduction: Although there is an increasing body of evidence that demonstrates that hydrogen sulfide (HS) provides significant protection against Ischemia Reperfusion Injury (IRI), the mechanism by which this protection is conferred remains poorly understood. The JAK-STAT signaling pathway is known to regulate multiple cell processes including proliferation, differentiation and apoptosis via modulation of nuclear gene expression. Previous work has shown that this pathway is activated by mechanical preconditioning, which provides protection against IRI. We hypothesize this critical cell survival pathway would be similarly activated by treatment with HS in the setting of IR.