Medicine by the Children

Aren't they beautiful? These are the 'simples' that my Jr. Herbalists made on Friday. We harvested together: wild oregano, wild mint, cleavers, mugwort, and yarrow. It was mostly up to them to figure out what plant went with what menstrum ... and I must say they did a stellar job!

IMPRESSIONS SHAPED BY FACIAL APPEARANCE FOSTER BIASED DECISIONS

Research in recent years has shown that people associate specific facial traits with an individual's personality. For instance, people consistently rate faces that appear more feminine or that naturally appear happy as looking more trustworthy. In addition to trustworthiness, people also consistently associate competence, dominance, and friendliness with specific facial traits. According to an article published by Cell Press on October 21st in Trends in Cognitive Sciences, people rely on these subtle and arbitrary facial traits to make important decisions, from voting for a political candidate to convicting a suspect for a crime. Referring to this systemic bias as "face-ism," the authors present its real-world consequences and discuss potential ways of overcoming it.

Although we would like to think our judgments and choices are rational, impartial, consistent, and solely based on relevant information, the truth is that they are often biased by superficial and irrelevant factors," says Christopher Olivola of Carnegie Mellon University's Tepper School of Business, lead author of the review article, which he co-authored with Princeton University researchers Friederike Funk and Alexander Todorov. "This is a troubling human tendency that needs to be corrected, or at least mitigated, because faces are not valid predictors of a person's traits."

Numerous studies have shown that people form impressions of aspiring leaders based on their faces, and that these superficial impressions predict important social outcomes. For example, political candidates with naturally competent-looking faces are more likely to win elections than those who look incompetent, and having a naturally dominant-looking face predicts rank attainment in the military.

The bias to rely on facial appearance to make decisions can also lead to serious consequences in the legal system and financial realm. People are more likely to convict individuals whose faces look untrustworthy or guilty, while having a face that looks trustworthy strengthens an individual's ability to attract financial investments and procure loans.

Uncovering the facial variations that lead to impressions of competence or trustworthiness is still an active area of research. Although much remains unknown, recent methodological advances, such as sophisticated computer-based models that systematically manipulate facial appearance, are allowing researchers to tackle this question with unprecedented rigor.

Although face-ism is widespread, research suggests that it could be reduced by arming people with more relevant and valid types of information. For instance, knowing more about a political candidate and his or her positions or past behavior makes voters less likely to be influenced by facial traits. "We need to guard against letting our choices be biased by superficial cues," Olivola says. "In some contexts, educating people might be sufficient to reduce facial stereotyping. In other contexts, however, more research will be needed to identify the best way to mitigate the biasing influence of facial appearance."

ACTIVATING HAIR GROWTH BY MODIFYING IMMUNE CELLS

How to restore hair loss is a task not undertaken exclusively by beauty practitioners. The discovery, now published by a group from the Spanish National Cancer Research Centre (CNIO), reveals a novel angle to spur hair follicle growth. This also adds new knowledge to a broader problem: how to regenerate tissues in an adult organism, especially the skin.

 The group has discovered an unexpected connection--a link between the body's defense system and skin regeneration. According to the authors of the study published today in PLOS Biology, cells from the immune system called macrophages-- those in charge of devouring invading pathogens, for example--are also responsible for activating skin stem cells and induce hair growth.

The regenerative ability of stem cells allows skin replenishment during a lifetime. But different factors can reduce their regenerative properties or promote their uncontrolled growth. When things go wrong, this can lead to aging and disease, including skin carcinomas. The discovery that macrophages activate skin stem cells may also have further implications beyond the possibility to develop therapeutic approaches for hair loss, but may also be relevant for cancer research.

The authors of the study are Mirna Perez-Moreno and Donatello Castellana, from the Epithelial Cell Biology Group of the BBVA Foundation-CNIO Cancer Cell Biology Programme, along with Ralf Paus, a hair immunobiology expert from the University of Manchester and Münster.

"We have discovered that macrophages, cells whose main function is traditionally attributed to fight infections and wound repair, are also involved in the activation of hair follicle stem cells in non inflamed skin," says Perez-Moreno.

The researchers did not investigate the relationship between macrophages and hair for fun. This work emerged more than four years ago from an observation made by Perez-Moreno while working on another research project. The mice she had been working with at that time received anti-inflammatory drugs, a treatment that also reactivated hair growth. Convinced that the explanation could reside in the existence of close communication between stem cells and immune cells --the Perez-Moreno's lab began to experiment with the different types of cells involved in the body´s defense system.

After years of investigation, they discovered that when stem cells are dormant, a fraction of macrophages die, due to a process known as apoptosis. This stimulated the secretion of factors from dying and living macrophages, which in turn activated stem cells, and that is when hairs began to grow again.

Reproducing natural process

Macrophages secrete a number of factors including a class of proteins called Wnt.

Researchers demonstrated the participation of macrophage-derived Wnts by artificially reproducing the natural process by treating macrophages with a Wnt inhibitor drug encapsulated in liposomes. As expected, when they used this drug, the activation of hair growth was delayed.

Although this study has been completed in mice, the researchers believe their discovery "may facilitate the development of novel treatment strategies" for hair growth in humans.

The possibility of attacking one type of cell to affect another might have broader applications that go beyond "just" growing hair. Furthermore, the use of liposomes as a way of drug delivery to specific cells, is a very promising line of experimentation, which may have implications for the study of several pathologies, says Donatello Castellana.

From a more fundamental perspective, this research is an effort to understand how modifying the environment that surrounds adult skin stem cells can regulate their regenerative capabilities. "One of the current challenges in the stem cell field is to regulate the activation of endogenous stem cell pools in adult tissues to promote regeneration without the need of transplantation," says Perez-Moreno.

Biochemical dialogue

It is now known that macrophages are key cells involved in the biochemical dialogue that exists in the environment surrounding stem cells.

"Our study underlines the importance of macrophages as modulators in skin regenerative processes, going beyond their primary function as phagocytes [immune system cells]," say the authors in PLoS Biology.

The researcher´s next goal is to characterise the class of macrophage(s) that are involved in the activation of skin stem cells and their implications in the regulation of stem cells under pathological conditions, including skin carcinomas.

As Perez-Moreno explains, "macrophages are a very diverse cell population. It was only less that ten years ago that scientists discovered that besides from the bone marrow, macrophages originate from the yolk sac during pregnancy, and there are even other macrophages that proliferate within tissues. The diversity of the sources from which skin resident macrophages originate is not fully understood."

ON OFF SWITCH FOR AGING CELLS DISCOVERED BY SCIENTISTS

Scientists at the Salk Institute have discovered an on-and-off “switch” in cells that may hold the key to healthy aging. This switch points to a way to encourage healthy cells to keep dividing and generating, for example, new lung or liver tissue, even in old age.

In our bodies, newly divided cells constantly replenish lungs, skin, liver and other organs. However, most human cells cannot divide indefinitely–with each division, a cellular timekeeper at the ends of chromosomes shortens. When this timekeeper, called a telomere, becomes too short, cells can no longer divide, causing organs and tissues to degenerate, as often happens in old age. But there is a way around this countdown: some cells produce an enzyme called telomerase, which rebuilds telomeres and allows cells to divide indefinitely.

In a new study published September 19 in the journalGenes and Development, scientists at the Salk Institute have discovered that telomerase, even when present, can be turned off.

“Previous studies had suggested that once assembled, telomerase is available whenever it is needed,” says senior author Vicki Lundblad, professor and holder of Salk’s Ralph S. and Becky O'Connor Chair. “We were surprised to discover instead that telomerase has what is in essence an ‘off’ switch, whereby it disassembles.”

Understanding how this “off” switch can be manipulated–thereby slowing down the telomere shortening process–could lead to treatments for diseases of aging (for example, regenerating vital organs later in life).

Lundblad and first author and graduate student Timothy Tucey conducted their studies in the yeast Saccharomyces cerevisiae, the same yeast used to make wine and bread. Previously, Lundblad’s group used this simple single-celled organism to reveal numerous insights about telomerase and lay the groundwork for guiding similar findings in human cells.

“We wanted to be able to study each component of the telomerase complex but that turned out to not be a simple task,” Tucey said. Tucey developed a strategy that allowed him to observe each component during cell growth and division at very high resolution, leading to an unanticipated set of discoveries into how–and when–this telomere-dedicated machine puts itself together.

Every time a cell divides, its entire genome must be duplicated. While this duplication is going on, Tucey discovered that telomerase sits poised as a “preassembly” complex, missing a critical molecular subunit. But when the genome has been fully duplicated, the missing subunit joins its companions to form a complete, fully active telomerase complex, at which point telomerase can replenish the ends of eroding chromosomes and ensure robust cell division.

Surprisingly, however, Tucey and Lundblad showed that immediately after the full telomerase complex has been assembled, it rapidly disassembles to form an inactive “disassembly” complex — essentially flipping the switch into the “off” position. They speculate that this disassembly pathway may provide a means of keeping telomerase at exceptionally low levels inside the cell. Although eroding telomeres in normal cells can contribute to the aging process, cancer cells, in contrast, rely on elevated telomerase levels to ensure unregulated cell growth. The “off” switch discovered by Tucey and Lundblad may help keep telomerase activity below this threshold.