High Spatial Resolution MALDI Imaging Mass Spectrometry of Fresh-Frozen Bone.

Bone and bone marrow are vital to mammalian structure, movement, and immunity. These tissues are also commonly subjected to molecular alterations giving rise to debilitating diseases like rheumatoid arthritis and osteomyelitis. Technologies such as matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) facilitate the discovery of spatially resolved chemical information in biological tissue samples to help elucidate the complex molecular processes underlying pathology. Traditionally, preparation of osseous tissue for MALDI IMS has been difficult due to its mineralized composition and heterogeneous morphology, and compensation for these challenges with decalcification and fixation protocols can remove or delocalize molecular species. Here, sample preparation methods were advanced to enable multimodal MALDI IMS of undecalcified, fresh-frozen murine femurs, allowing the distribution of endogenous lipids to be linked to tissue structures and cell types. Adhesive-bound bone sections were mounted onto conductive glass slides with microscopy-compatible glue and freeze-dried to minimize artificial bone marrow damage. High spatial resolution (10 µm) MALDI IMS was employed to characterize lipid distributions, and use of complementary microscopy modalities aided tissue and cell assignments. For example, various phosphatidylcholines localize to the bone marrow, adipose tissue, marrow adipose tissue, and muscle. Further, sphingomyelin(42:1) was abundant in megakaryocytes, whereas sphingomyelin(42:2) was diminished in this cell type. These data reflect the vast molecular and cellular heterogeneity indicative of the bone marrow and the soft tissue surrounding the femur. Multimodal MALDI IMS has the potential to advance bone-related biomedical research by offering deep molecular coverage with spatial relevance in a preserved native bone microenvironment.

Chiropractic Identity in the United States: Wisdom, Courage, and Strength.

OBJECTIVE: The objective of this paper was to discuss the chiropractic profession's identity and 3 contentious issues related to identity. DISCUSSION: The various clinical specialties and independent groups in the chiropractic profession are so different in their beliefs, practice styles, and political agendas that a common identity is unlikely to be created. Areas of disagreement, including advanced practice, vertebral subluxation, and the philosophy of chiropractic, continue to separate those in the profession. Doctors of chiropractic should accept that differences within the profession will remain for the foreseeable future and that the profession should allow each group to live peacefully and supportively alongside each other. CONCLUSIONS: If the profession embraces the ideals of truth, respect, and tolerance, it can continue to grow and provide diverse health care services well into the future.