Magic Bullet for Nail Biting

Image of a person biting their fingernails

By Guest Bloggers Han Peng, PhD & Robert M. Lavker, PhD
Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL


“Stop biting your nails!” parents scold their children.

Now we have more evidence why parents are correct in this admonishment. Nail biters, here is the latest scientific warning: Do not bite your nails too deeply; otherwise, you may lose the ability to regenerate the nail (and digit, if you are an Olympic nail-biter), according to Takeo et al in a recent article published in Nature.

The ability to regenerate nails and digit-tips in mice requires wnt signals initiated by the nail distal matrix; this is supported by evidence that loss of wnt signal (by either conditional knockout of β-catenin or removal of the distal matrix) results in failure of nail differentiation and bone regeneration.

Given the wnt signaling links between nail differentiation and digit regeneration, Takeo and colleagues investigated whether giving a wnt signal to nail epithelium can overcome the limitation of regeneration after removal of the distal matrix. Indeed, stabilization of β-catenin in the basal nail epithelium, which includes the nail epithelial stem cells, leads to regeneration of wnt-active distal nail matrix, formation of an innervated blastema, bone regeneration, and nail regrowth. Therefore, from the bench-to-bedside of view, nail epithelial stem cells may have the potential for the development of a stem cell therapy for amputees, if the proper signals were given. In the short-term, congenital nail biters might have a way out; a nail polish containing slow release, activated, Wnt nanoparticles, which could penetrate the nail plate and maintain nail viability.


Takeo M, Chou WC, Sun Q (2013) Wnt activation in nail epithelium couples nail growth to digit regeneration. Nature 499:228-232

Drop of tar captured on film after nearly 70 years of waiting

The world has waited a mere nine months for the new royal prince . . . but the world has been waiting much longer for a drop of liquid to come from tar-pitch (asphalt), proving that it is a liquid. It just happened — after nearly 70 years of waiting. Sadly, another  group of researches missed the drop in their  experiment, and their children are now waiting to see if they can confirm the experiment. Patience is a virtue, and being first with the data wins the race — even if it is a slow race. See the details of the role of coal tar in new skin drug development in the March 26, 2013 blog.


Image used with permission of David Whyte, Trinity College Dublin

Arginase — Nexus for Wound Healing

Arginase has a rich history in cutaneous biology and pathophysiology, as discussed in this blog on August 1, 2102. It is a topic, like a cicada, that raises its head annually. Its role in wound healing was further investigated by Campbell et al (2013). Arginase was deleted in alternatively activated macrophages, and this enzyme, which  increases several-fold during wound healing in the mouse, was abrogated.  Arginase usually peaks five days after an excisional wound;  in the arginase knockout there was increased inflammation and slowed healing. Chemical inhibitors of arginase mimicked the effects seen in the knockout mouse.  Arginase modulation might be therapeutically useful in wounds with abnormal healing (e.g., keloids or hypertrophic scars) and in wounds with decreased healing, as occurs commonly in diabetes, aging, vascular diseases.  Like other physiological pathways — following the Goldilocks principle may be important, you need just the right amount: not too much and not too little.



Campbell L, Saville CR, Murray PJ, et al (2013) Local Arginase 1 Activity Is Required for Cutaneous Wound Healing. J Invest Dermatol doi:10.1038/jid.2013.164



The questions and answers below relate to the Research Techniques Made Simple article  “Enzyme Immunoassay (EIA) and Enzyme-Linked Immunosorbent Assay (ELISA),” published online with the September 2013 issue of JID.


Correct answers appear in bold underline.


Multiple Choice Questions & Answers:


1.    Which of the following molecule(s) can be detected by ELISA?

a)     proteins

b)     hormones

c)     antibodies

d)     all of the above


2.     What does a weak color signal in competitive ELISA represent?

a)     more antigen in the sample

b)     less antigen in the sample

c)     less antigen retained on the well

d)     both a and c


3.    Which of the following is immobilized on the microtiter well in sandwich ELISA?

a)    detection antibody

b)    sample

c)    capture antibody

d)    secondary antibody conjugated to an enzyme


4.    What is a major advantage of ELISA in comparison to other biological quantification techniques?

a)    detection of a molecule at a low concentration

b)    inexpensive

c)    low specificity

d)    easily available


The questions and answers below relate to the Research Techniques Made Simple article  “Next Generation Sequencing: Methodology and Application,” published online with the August 2013 issue of JID.

Correct answers appear in bold underline


Multiple Choice Questions & Answers:


1.     The basic methodological steps of NGS include:

a)     Template preparation, emulsion PCR, sequencing, data analysis

b)     Template preparation, sequencing and imaging, data analysis

c)     Template amplification, sequencing and imaging, data analysis

d)     Template preparation, sequencing and imaging, alignment to a reference genome

e)     DNA fragmentation, sequencing, data analysis



2.     Advantages of targeted sequencing as opposed to full genome, exome, or transcriptome sequencing include:

a)     Affordable and efficient for quickly interrogating particular genomic regions of interest

b)     Provides a deeper coverage of genomic regions of interest

c)     Can be utilized in deciding a therapeutic plan of action for both germline and somatic cancers

d)     Detects and quantifies low-frequency variants such as rare drug-resistant viral mutations (e.g., HIV, HBV or microbial pathogens)

e)     All of the above



3.     Applications of NGS in medicine include:

a)     Detecting mutations that play a role in diseases such as cancer

b)     Identifying genes responsible for inherited skin diseases

c)     Determining RNA expression levels

d)     Identifying novel virulence factors through sequencing of bacterial and viral species

e)     All of the above

Roots and Routes

By GUEST BLOGGER Ethan Lerner, MD, PhD of Massachusetts General Hospital


A 10-year billion-dollar plan is afoot to map all of the connections in the brain. The plan is called the BRAIN initiative, or Connectome. Pretty pictures have already been posted. Really. And really pretty. Perhaps we should concurrently tackle the “Peripherome” – the neural routes from the skin to the dorsal root ganglia and on to the spinal cord. The Peripherome should be sensational to cutaneous biology as it informs us about all sorts of sensations: Itch, touch, pressure, heat, cold, pain, and, with a bit of luck, pleasure. We might even learn a thing or two about hair and sweat, as follicles and glands are highly innervated.


Readers may be interested in the recent Science article by Mishra and Hoon (The Cells and Circuitry for Itch Responses in Mice).


Image courtesy of the Laboratory of Neuro Imaging at UCLA and Martinos Center for Biomedical Imaging at MGH, Consortium of the Human Connectome Project –  (White matter fiber architecture of the brain. Measured from diffusion spectral imaging (DSI). The fibers are color-coded by direction: red = left-right, green = anterior-posterior, blue = through brain stem.)