A brief review of recent discoveries in human anatomy

Novel strategy of combined interstitial macrophage depletion with intravenous targeted therapy to ameliorate pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a severe interstitial lung disease with poor prognosis and high mortality rate. In the process of IPF, inflammatory dysregulation of macrophages and massive fibroblast aggregation and proliferation destroy alveoli, which cause pulmonary dysfunction, and ultimately lead to death due to respiratory failure. In the treatment of IPF, crossing biological barriers and delivering drugs to lung interstitium are the major challenges. In order to avoid the side effect of macrophages proliferation, we proposed, designed, and evaluated the strategy which combined macrophage depletion by intervaginal space injection and intravenous targeted therapy on bleomycin mouse model. We found that it inhibited pulmonary macrophages, reduced macrophage depletion in non-target organs, improved pulmonary drug targeting, impeded the progression of pulmonary fibrosis, and accelerated the recovery of pulmonary function. This combination therapeutic strategy shows good biosafety and efficacy, induces a targeted response, and is promising as a practical new clinical approach towards the treatment of pulmonary fibrosis.

Using Stereoscopic Virtual Presentation for Clinical Anatomy Instruction and Procedural Training in Medical Education

This chapter begins by exploring the current landscape of virtual and augmented reality technologies in a post-pandemic world and asserting the importance of virtual technologies that improve students' learning outcomes while also reducing costs. Next, the chapter describes clinical anatomy instruction concepts in medical education, including applied anatomy content knowledge, pedagogical anatomy content knowledge, and virtual stereoscopic visualization studies that exemplify these concept areas, respectively. The chapter then explores the concept of procedural training with a specific emphasis on virtual stereoscopic anatomy visualization studies that exemplify or have implications for procedural training in medical education. Subsequently, the chapter discusses the benefits and challenges as well as the potential future positive and negative implications of virtual stereoscopic visualizations in medical education before finally concluding with some pensive considerations for the present and future of anatomy education and training using virtual technologies.

Hydroxysafflor Yellow A Phytosomes Administered via Intervaginal Space Injection Ameliorate Pulmonary Fibrosis in Mice

Idiopathic pulmonary fibrosis is a fatal interstitial disease characterized by fibroblast proliferation and differentiation and abnormal accumulation of extracellular matrix, with high mortality and an increasing annual incidence. Since few drugs are available for the treatment of pulmonary fibrosis, there is an urgent need for high-efficiency therapeutic drugs and treatment methods to reduce the mortality associated with pulmonary fibrosis. The interstitium, a highly efficient transportation system that pervades the body, plays an important role in the occurrence and development of disease, and can be used as a new route for disease diagnosis and treatment. In this study, we evaluated the administration of hydroxysafflor yellow A phytosomes via intervaginal space injection (ISI) as an anti-pulmonary fibrosis treatment. Our results show that this therapeutic strategy blocked the activation of p38 protein in the MAPK-p38 signaling pathway and inhibited the expression of Smad3 protein in the TGF-β/Smad signaling pathway, thereby reducing secretion of related inflammatory factors, deposition of collagen in the lungs of mice, and destruction of the alveolar structure. Use of ISI in the treatment of pulmonary fibrosis provides a potential novel therapeutic modality for the disease.

Are We Facing the End of Gross Anatomy Teaching as We Have Known It for Centuries?

The status of anatomy education in undergraduate medical education has dramatically changed over the course of the past century. From the most important and time-consuming component of the preclinical program, anatomy education has reduced in size and status, and yielded in curricular space to accommodate other disciplines and topics. Meanwhile, radiology has become more prominent, as a means to visualize anatomy, not only in clinical care but also in education. For this perspective paper, the authors, all with backgrounds in anatomy, radiology and/or medical education, conducted structured conversations with several academic colleagues with similar backgrounds, reviewed pertinent literature and analyzed the causes of the historical decline of a knowledge domain of medical education, that nevertheless is widely considered essential for medical students and graduates. After this analysis, the authors propose four ways forward. These directions include systematic peer teaching and development of anatomy education as a scholarly domain, further vertical integration with postgraduate medical education, full integration with radiology education, and capitalizing on educational technology. Schools in several industrialized countries have made steps in these directions, which can be further strengthened. In less affluent countries, and in countries with curricula strongly determined by tradition, these steps are less easy to make. To respond to changes in global health and health care, combined with the inevitable technological progress, and international mobility, we believe all schools will move in these directions, slower or faster.

Clearance Systems in the Brain, From Structure to Function

As the most metabolically active organ in the body, there is a recognized need for pathways that remove waste proteins and neurotoxins from the brain. Previous research has indicated potential associations between the clearance system in the brain and the pathological conditions of the central nervous system (CNS), due to its importance, which has attracted considerable attention recently. In the last decade, studies of the clearance system have been restricted to the glymphatic system. However, removal of toxic and catabolic waste by-products cannot be completed independently by the glymphatic system, while no known research or article has focused on a comprehensive overview of the structure and function of the clearance system. This thesis addresses a neglected aspect of linkage between the structural composition and main components as well as the role of neural cells throughout the clearance system, which found evidence that the components of CNS including the glymphatic system and the meningeal lymphatic system interact with a neural cell, such as astrocytes and microglia, to carry out vital clearance functions. As a result of this evidence that can contribute to a better understanding of the clearance system, suggestions were identified for further clinical intervention development of severe conditions caused by the accumulation of metabolic waste products and neurotoxins in the brain, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD).

Cerebral Microcirculation, Perivascular Unit, and Glymphatic System: Role of Aquaporin-4 as the Gatekeeper for Water Homeostasis

In the past, water homeostasis of the brain was understood as a certain quantitative equilibrium of water content between intravascular, interstitial, and intracellular spaces governed mostly by hydrostatic effects i.e., strictly by physical laws. The recent achievements in molecular bioscience have led to substantial changes in this regard. Some new concepts elaborate the idea that all compartments involved in cerebral fluid homeostasis create a functional continuum with an active and precise regulation of fluid exchange between them rather than only serving as separate fluid receptacles with mere passive diffusion mechanisms, based on hydrostatic pressure. According to these concepts, aquaporin-4 (AQP4) plays the central role in cerebral fluid homeostasis, acting as a water channel protein. The AQP4 not only enables water permeability through the blood-brain barrier but also regulates water exchange between perivascular spaces and the rest of the glymphatic system, described as pan-cerebral fluid pathway interlacing macroscopic cerebrospinal fluid (CSF) spaces with the interstitial fluid of brain tissue. With regards to this, AQP4 makes water shift strongly dependent on active processes including changes in cerebral microcirculation and autoregulation of brain vessels capacity. In this paper, the role of the AQP4 as the gatekeeper, regulating the water exchange between intracellular space, glymphatic system (including the so-called neurovascular units), and intravascular compartment is reviewed. In addition, the new concepts of brain edema as a misbalance in water homeostasis are critically appraised based on the newly described role of AQP4 for fluid permeation. Finally, the relevance of these hypotheses for clinical conditions (including brain trauma and stroke) and for both new and old therapy concepts are analyzed.

Glymphatic System as a Gateway to Connect Neurodegeneration From Periphery to CNS

The classic concept of the absence of lymphatic vessels in the central nervous system (CNS), suggesting the immune privilege of the brain in spite of its high metabolic rate, was predominant until recent times. On the other hand, this idea left questioned how cerebral interstitial fluid is cleared of waste products. It was generally thought that clearance depends on cerebrospinal fluid (CSF). Not long ago, an anatomically and functionally discrete paravascular space was revised to provide a pathway for the clearance of molecules drained within the interstitial space. According to this model, CSF enters the brain parenchyma along arterial paravascular spaces. Once mixed with interstitial fluid and solutes in a process mediated by aquaporin-4, CSF exits through the extracellular space along venous paravascular spaces, thus being removed from the brain. This process includes the participation of perivascular glial cells due to a sieving effect of their end-feet. Such draining space resembles the peripheral lymphatic system, therefore, the term "glymphatic" (glial-lymphatic) pathway has been coined. Specific studies focused on the potential role of the glymphatic pathway in healthy and pathological conditions, including neurodegenerative diseases. This mainly concerns Alzheimer's disease (AD), as well as hemorrhagic and ischemic neurovascular disorders; other acute degenerative processes, such as normal pressure hydrocephalus or traumatic brain injury are involved as well. Novel morphological and functional investigations also suggested alternative models to drain molecules through perivascular pathways, which enriched our insight of homeostatic processes within neural microenvironment. Under the light of these considerations, the present article aims to discuss recent findings and concepts on nervous lymphatic drainage and blood-brain barrier (BBB) in an attempt to understand how peripheral pathological conditions may be detrimental to the CNS, paving the way to neurodegeneration.

Mesentery - a 'New' organ

The mesentery is the organ in which all abdominal digestive organs develop, and which maintains these in systemic continuity in adulthood. Interest in the mesentery was rekindled by advancements of Heald and Hohenberger in colorectal surgery. Conventional descriptions hold there are multiple mesenteries centrally connected to the posterior midline. Recent advances first demonstrated that, distal to the duodenojejunal flexure, the mesentery is a continuous collection of tissues. This observation explained how the small and large intestines are centrally connected, and the anatomy of the associated peritoneal landscape. In turn it prompted recategorisation of the mesentery as an organ. Subsequent work demonstrated the mesentery remains continuous throughout development, and that abdominal digestive organs (i.e. liver, spleen, intestine and pancreas) develop either on, or in it. This relationship is retained into adulthood when abdominal digestive organs are directly connected to the mesentery (i.e. they are 'mesenteric' in embryological origin and anatomical position). Recognition of mesenteric continuity identified the mesenteric model of abdominal anatomy according to which all abdominal abdomino-pelvic organs are organised into either a mesenteric or a non-mesenteric domain. This model explains the positional anatomy of all abdominal digestive organs, and associated vasculature. Moreover, it explains the peritoneal landscape and enables differentiation of peritoneum from the mesentery. Increased scientific focus on the mesentery has identified multiple vital or specialised functions. These vary across time and in anatomical location. The following review demonstrates how recent advances related to the mesentery are re-orientating the study of human biology in general and, by extension, clinical practice.

Possible routes of SARS-CoV-2 invasion in brain: In context of neurological symptoms in COVID-19 patients

Manifestation of neurological symptoms in certain patients of coronavirus disease-2019 (COVID-19) has warranted for their virus-induced etiogenesis. SARS-CoV-2, the causative agent of COVID-19, belongs to the genus of betacoronaviruses which also includes SARS-CoV-1 and MERS-CoV; causative agents for severe acute respiratory syndrome (SARS) in 2002 and Middle East respiratory syndrome (MERS) in 2012, respectively. Studies demonstrating the neural invasion of SARS-CoV-2 in vivo are still scarce, although such characteristics of certain other betacoronaviruses are well demonstrated in the literature. Based on the recent evidence for the presence of SARS-CoV-2 host cell entry receptors in specific components of the human nervous and vascular tissue, a neural (olfactory and/or vagal), and a hematogenous-crossing the blood-brain barrier, routes have been proposed. The neurological symptoms in COVID-19 may also arise as a consequence of the "cytokine storm" (characteristically present in severe disease) induced neuroinflammation, or co-morbidities. There is also a possibility that, there may be multiple routes of SARS-CoV-2 entry into the brain, or multiple mechanisms can be involved in the pathogenesis of the neurological symptoms. In this review article, we have discussed the possible routes of SARS-CoV-2 brain entry based on the emerging evidence for this virus, and that available for other betacoronaviruses in literature.

Neglected interstitial space in malaria recurrence and treatment

The interstitial space, a widespread fluid-filled compartment throughout the body, is related to many pathophysiological alterations and diseases, attracting increasing attention. The vital role of interstitial space in malaria infection and treatment has been neglected current research efforts. We confirmed the reinfection capacity of parasites sequestrated in interstitial space, which replenish the mechanism of recurrence. Malaria parasite-infected mice were treated with artemisinin-loaded liposomes through the interstitial space and exhibited a better therapeutic response. Notably, compared with oral administration, interstitial administration showed an unexpectedly high activation and recruitment of immune cells, and resulted in better clearance of sequestered parasites from organs, and enhanced pathological recovery. The interstitial route of administration prolongs the blood circulation time of artemisinin and increases its plasma concentration, and may compensate for the inefficiency of oral administration and the nanotoxicity of intravenous administration, providing a potential strategy for infectious disease therapy.