Adhesive and mechanical regulation of mesenchymal stem cell differentiation in human bone marrow and periosteum-derived progenitor cells

It has previously been demonstrated that cell shape can influence commitment of human bone marrow-derived mesenchymal stem cells (hBMCs) to adipogenic, osteogenic, chondrogenic, and other lineages. Human periosteum-derived cells (hPDCs) exhibit multipotency similar to hBMCs, but hPDCs may offer enhanced potential for osteogenesis and chondrogenesis given their apparent endogenous role in bone and cartilage repair in vivo. Here, we examined whether hPDC differentiation is regulated by adhesive and mechanical cues comparable to that reported for hBMC differentiation. When cultured in the appropriate induction media, hPDCs at high cell seeding density demonstrated enhanced levels of adipogenic or chondrogenic markers as compared with hPDCs at low cell seeding density. Cell seeding density correlated inversely with projected area of cell spreading, and directly limiting cell spreading with micropatterned substrates promoted adipogenesis or chondrogenesis while substrates promoting cell spreading supported osteogenesis. Interestingly, cell seeding density influenced differentiation through both changes in cell shape and non-shape-mediated effects: density-dependent adipogenesis and chondrogenesis were regulated primarily by cell shape whereas non-shape effects strongly influenced osteogenic potential. Inhibition of cytoskeletal contractility by adding the Rho kinase inhibitor Y27632 further enhanced adipogenic differentiation and discouraged osteogenic differentiation of hPDCs. Together, our results suggest that multipotent lineage decisions of hPDCs are impacted by cell adhesive and mechanical cues, though to different extents than hBMCs. Thus, future studies of hPDCs and other primary stem cell populations with clinical potential should consider varying biophysical metrics for more thorough optimization of stem cell differentiation.R01 EB000262 - NIBIB NIH HHS; R01 GM060692 - NIGMS NIH HHSPublished versio

The Meaning of Meaningful Work: Subject-Object Meaningfulness in Knowledge Work

Highest Honors (Bachelor's)Organizational StudiesUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/134384/1/graceac.pd

Western and Chinese Medicine in the History of Community-Based Care in San Francisco’s Chinatown

In fear-inciting epidemic, disease has often led to the disproportionate injury of minority communities through lack of equal access to medical care and implementation of prejudiced policies disguised as public health. In the United States, the use of infectious disease as a vehicle for the targeted suppression of Chinese Americans is no new phenomenon, from the discriminatory reactions to the 1900 San Francisco plague outbreak to the escalation of racial violence in the ongoing coronavirus pandemic. Here, I explore how Chinese immigrants in the late 19th and early 20th centuries responded to inadequate public health care in San Francisco, including through the bubonic plague outbreak. From the earliest examples of community-based care to the establishment of the first and only Chinese Hospital in the country, I trace how these immigrants hybridized Western and Chinese medicine in their efforts to establish the quality medical care they had been refused for decades

Chromatin Laser Imaging Reveals Abnormal Nuclear Changes for Early Cancer Detection

We developed and applied rapid scanning laser-emission microscopy to detect abnormal changes in cell nuclei for early diagnosis of cancer and cancer precursors. Regulation of chromatins is essential for genetic development and normal cell functions, while abnormal nuclear changes may lead to many diseases, in particular, cancer. The capability to detect abnormal changes in apparently normal tissues at a stage earlier than tumor development is critical for cancer prevention. Here we report using LEM to analyze colonic tissues from mice at-risk for colon cancer by detecting prepolyp nuclear abnormality. By imaging the lasing emissions from chromatins, we discovered that, despite the absence of observable lesions, polyps, or tumors under stereoscope, high-fat mice exhibited significantly lower lasing thresholds than low-fat mice. The low lasing threshold is, in fact, very similar to that of adenomas and is caused by abnormal cell proliferation and chromatin deregulation that can potentially lead to cancer. Our findings suggest that conventional methods, such as colonoscopy, may be insufficient to reveal hidden or early tumors under development. We envision that this work will provide new insights into LEM for early tumor detection in clinical diagnosis and fundamental biological and biomedical research of chromatin changes at the biomolecular level of cancer development

Improving the system capacity of broadband services using multiple high-altitude platforms

A method of significantly improving the capacity of high-altitude platform (HAP) communications networks operating in the millimeter-wave bands is presented. It is shown how constellations of HAPs can share a common frequency allocation by exploiting the directionality of the user antenna. The system capacity of such constellations is critically affected by the minimum angular separation of the HAPs and the sidelobe level of the user antenna. For typical antenna beamwidths of approximately 5/spl deg/ an inter-HAP spacing of 4 km is sufficient to deliver optimum performance. The aggregate bandwidth efficiency is evaluated, both theoretically using the Shannon equation, and using practical modulation and coding schemes, for multiple HAP configurations delivering either single or multiple cells. For the user antenna beamwidths used, it is shown that capacity increases are commensurate with the increase in the number of platforms, up to 10 HAPs. For increases beyond this the choice of constellation strategy becomes increasingly important

Multiple high-pressure phase transitions in BiFeO3

We investigate the high-pressure phase transitions in BiFeO3 by single crystal and powder x-ray diffraction, as well as single crystal Raman spectroscopy. Six phase transitions are reported in the 0-60 GPa range. At low pressures, up to 15 GPa, 4 transitions are evidenced at 4, 5, 7 and 11 GPa. In this range, the crystals display large unit cells and complex domain structures, which suggests a competition between complex tilt systems and possibly off-center cation displacements. The non polar Pnma phase remains stable over a large pressure range between 11 and 38 GPa, where the distortion (tilt angles) changes only little with pressure. The two high-pressure phase transitions at 38 and 48 GPa are marked by the occurence of larger unit cells and an increase of the distorsion away from the cubic parent perovskite cell. We find no evidence for a cubic phase at high pressure, nor indications that the structure tends to become cubic. The previously reported insulator-to-metal transition at 50 GPa appears to be symmetry breaking.Comment: 11 pages, 8 figure