Posts Tagged ‘anatomy’

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by SUKANYA CHARUCHANDRA

It wasn’t until the latter half of the 13th century that human dissections became acceptable in Italy. Previously, both the Roman Empire and Islamic law had prevented the dissection of humans and its depiction. While the Greek surgeon Galen’s anatomical drawings from the second century had been preserved and studied until the Renaissance, they were largely based on dissections of animals, such as apes.

In the mid-16th century, however, famed Flemish anatomist Andreas Vesalius dissected the bodies of executed criminals—not an uncommon practice in that period—while studying in Paris. He realized that Galen had been “misled” by apes, whose anatomy was not exactly like that of humans.

“The challenge of anatomy is rendering the 3-D experience of opening bodies onto a 2-D page,” writes Hannah Marcus, a science historian at Harvard University, in an email to The Scientist. Lack of refrigeration also presented a challenge. In overcoming those hurdles to produce the first realistic depictions of internal human biology, Vesalius’s De Humani Corporis Fabrica, published in Basel, Switzerland, in 1543, galvanized the study of anatomy.

Meanwhile, Spanish-born Juan Valverde de Amusco was learning anatomy under the guidance of Roman surgeon Realdo Colombo, and possibly of Vesalius himself, at the University of Padua in Italy. Valverde observed and participated in many dissections under Colombo’s guidance, and pored over old books on the subject. He later moved to Rome and was welcomed into the home of Spanish Cardinal Juan Álvarez de Toledo.

In 1555, Valverde served as a doctor at the foremost contemporaneous Roman hospital, Santo Spirito, where many luminaries of anatomy worked during that period, including Bartolomeo Eustachi, under whom Valverde studied for a time. The following year, Valverde crafted the Spanish-language anatomical text Historia de la Composicion del Cuerpo Humano, or Account of the Composition of the Human Body. In seven parts, the book covered topics such as “bone and cartilage,” “ligaments and bandaging,” and “instruments of sensation and external motion.” Largely copied from the 1543 and 1555 editions of Vesalius’s tome, it included 15 new illustrations in four copper plates. Valverde’s book also included more than 60 corrections to Vesalius’s text, which enhanced the contemporary understanding of the intracranial passage of carotid arteries, the extraocular muscles, the stapes bone of the middle ear, and how blood moves through the septum. Historians attribute the few original illustrations to Spanish-born Gaspar Becerra.

“Vesalius was angry about Amusco’s work and accused him of plagiarism,” Marcus writes. In 1564, Vesalius wrote in his book Anatomicarum Gabrielis Fallopii Observationum Examen that “Valverde who never put his hand to a dissection and is ignorant of medicine as well as of the primary disciplines, undertook to expound our art in the Spanish language only for the sake of shameful profit.” Valverde conceded his borrowing, explaining that Vesalius’s drawings were so thorough that “it would look like envy or malignity not to take advantage of them.”

Valverde simplified Vesalius’s Latin text considerably, however, as he considered it difficult to understand. His more concise (and thus cheaper) text had more than a dozen editions published in Italian, Latin, Dutch, and Greek, in addition to Spanish, and facilitated the spread of scientific ideas and Vesalius’s modern anatomy throughout Europe and the Spanish Americas.

https://www.the-scientist.com/foundations/homo-sapiens-exposed–1556-64679

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Ionocytes (orange) extend through neighboring epithelial cells (nuclei, cyan) to the surface of the respiratory epithelial lining. This newly identified cell type expresses high levels of CFTR, a gene that is associated with cystic fibrosis when mutated.

by ABBY OLENA

Two independent research teams have used single-cell RNA sequencing to generate detailed molecular atlases of mouse and human airway cells. The findings, reported in two studies today (August 1) in Nature, reveal the gene-expression patterns of thousands of lung cells, as well as the existence of a previously unknown cell type that expresses high levels of the gene mutated in cystic fibrosis, the cystic fibrosis transmembrane conductance regulator (CFTR).

“These papers are extremely exciting,” says Amy Ryan, a lung biologist at the University of Southern California who was not involved in either study. “They’ve interrogated the cellular composition and the cellular hierarchy of the airways by using a single-cell RNA-sequencing technique. That kind of information is going to have a significant impact on advancing the research that we can do, and hopefully the derivation of new therapeutic approaches for any number of airway diseases.”

Jayaraj Rajagopal, a pulmonary physician at Massachusetts General Hospital and Harvard University and coauthor of one of the studies, had been studying lung regeneration and wanted to use single-cell sequencing to look at differences in the lungs’ stem-cell populations. He and his colleagues teamed up with Aviv Regev, a computational biologist at the Broad Institute of MIT and Harvard University, and together, the two groups characterized the transcriptomes of thousands of epithelial cells from the adult mouse trachea.

Rajagopal, Regev, and colleagues uncovered previously unknown differences in gene expression in several groups of airway cells; identified novel structures in the lung; and found new paths of cellular differentiation. They also described several new cell types, including one that the team has named the pulmonary ionocyte, after salt-regulating cells in fish and amphibian skin. These lung cells express similar genes as fish and amphibian ionocytes, the team found, including a gene coding for the transcription factor Foxi1, which regulates genes that play a role in ion transport.

The team also showed that pulmonary ionocytes highly express CFTR, and are in fact the primary source of its product, CFTR—a membrane protein that helps regulate fluid transport and the consistency of mucus—in both mouse and human lungs, suggesting that the cells might play a role in cystic fibrosis.

“So much that we found rewrites the way we think about lung biology and lung cells,” says Rajagopal. “I think the entire community of pulmonologists and lung biologists will have to take a step back and think about their problems with respect to all these new cell types.”

For the other study, Aron Jaffe, a biologist at Novartis who studies how different airway cell types are made, combined forces with Harvard systems biologist Allon Klein and his team. Klein’s group had previously developed a single-cell RNA-sequencing method that Jaffe describes as “the perfect technology to take a big picture view and really define the full repertoire of epithelial cell types in the airway.”

Jaffe, Klein, and colleagues sequenced RNA from thousands of single human bronchial epithelial and mouse tracheal epithelial cells. The atlas generated by their sequencing analysis revealed pulmonary ionocytes, as well as new gene-expression patterns in familiar cells. The team examined the expression of CFTR in human and mouse ionocytes in order to better understand the possible role for the cells in cystic fibrosis. Consistent with the findings of the other study, the researchers showed that pulmonary ionocytes make the majority of CFTR protein in the airways of humans and mice.

“Finding this new rare cell type that accounts for the majority of CFTR activity in the airway epithelium was really the biggest surprise,” Jaffe tells The Scientist. “CFTR has been studied for a long time, and it was thought that the gene was broadly expressed in many cells in the airway. It turns out that the epithelium is more complicated than previously appreciated.”

These studies are “very exciting work [and] a wonderful example of how new technologies that have come online in the last few years—in this case single-cell RNA sequencing—have made a very dramatic advance in our understanding of aspects of biology,” says Ann Harris, a geneticist at Case Western Reserve University who did not participate in either study.

In terms of future directions, the authors “have shown that transcription factor [Foxi1] is central to the transcriptional program of these ionocytes,” says Harris. One of the next questions is, “does it directly interact with the CFTR gene or is it working through other transcription factors or other proteins that regulate CFTR gene expression?”

According to Jennifer Alexander-Brett, a pulmonary physician and researcher at Washington University School of Medicine in St. Louis who was not involved in the studies, the possibility that a rare cell type could be playing a part in regulating airway physiology is “captivating.”

Apart from investigating the potential role for ionocytes in lung function, Alexander-Brett says that researchers can likely make broad use of the data from the studies—particularly details on the expression of genes coding for transcription factors and cell-surface markers. “One area that we really struggle with in airway biology . . . is [that] we just don’t have good markers” to differentiate cell types, she explains. But these papers are “very comprehensive. There’s a ton of data here.”

D.T. Montoro et al., “A revised airway epithelial hierarchy includes CFTR-expressing ionocytes,” Nature, doi:10.1038/s41586-018-0393-7, 2018.

L.W. Plasschaert et al., “A single-cell atlas of the airway epithelium reveals the CFTR-rich pulmonary ionocyte,” Nature, doi:10.1038/s41586-018-0394-6, 2018.

https://www.the-scientist.com/news-opinion/new-lung-cell-identified-64594?utm_campaign=TS_DAILY%20NEWSLETTER_2018&utm_source=hs_email&utm_medium=email&utm_content=64924537&_hsenc=p2ANqtz-_M5n43mM_3CJb8-lIkjE6yt4ij2HduxgVeZi_X5bG7ATrAOGkvtsg4DpCbuAc0NAG8lx4myMxN3kiH4C1qc9OdlQkAGg&_hsmi=64924537


A newfound organ, the interstitium, resides beneath the top layer of skin, and in tissue layers lining the gut, lungs, blood vessels, and muscles. The organ is a body-wide network of interconnected, fluid-filled compartments supported by a meshwork of strong, flexible proteins.

Using a new way of visualising anatomy, scientists have just discovered a vast new structure in the human body that could be considered an organ in its own right.

The finding, published in the journal Scientific Reports, has important implications for our understanding of how all organs and tissues function, and could reveal previously unknown mechanisms driving diseases such as fibrosis and cancer.

But how could something so significant have gone unnoticed all this time?

It was well known that a layer of tissue lies just below the surface of the skin, and also lines the lungs, the digestive and urinary tracts, and much of the circulatory system. But it was thought this comprised little more than dense, connective tissue.

The new research reveals that it is actually a vast, interconnected system of fluid-filled compartments that extends all over the body.

That contents is extra-cellular, or “interstitial”, fluid. Accordingly, the structure has been dubbed “the interstitium”.

Until now, the interstitium had been hidden in plain sight because the traditional method of preparing microscope slides involves draining away fluid. This had caused the sacs to collapse, leaving only the supportive connective tissue visible.

But recently, researchers led by Neil Theise at New York University in the US began using probe-based confocal laser endomicroscopy, which aims laser light at living tissue and detects reflected fluorescent patterns, providing a different sort of microscopic image. While examining the bile duct of a cancer patient, they found a network of fluid-filled sacks that had never been seen before.

They soon found this network everywhere tissues are distended or compressed as part of normal function — which is quite a lot of the body — and propose that the interstitium may function as a shock absorber.

Its physical structure is certainly quite unusual: the fluid-filled spaces are supported by an extensive lattice of collagen bundles that are lined on only one side by what appear to be a type of stem cell.

These cells may help make collagen, and could aid in wound healing. Similarly, they could contribute to conditions associated with inflammation and ageing.

In addition to cushioning, the interstitium may have another important job. While it was known that interstitial fluid is the major source of lymph fluid, which carries immune cells throughout the body, just how it reaches the lymphatic system was unclear. The new research shows that the interstitium drains directly into the lymph nodes.

The study also shows that cancers, such as melanoma, are able to spread via the interstitium.

“This finding has potential to drive dramatic advances in medicine, including the possibility that the direct sampling of interstitial fluid may become a powerful diagnostic tool,” says Theise.

https://cosmosmagazine.com/biology/meet-your-interstitium