OVERVIEW. We will build a portable instrument for diagnosing zinc deficiency by the use of a quick, painless fingernail reading taken in the field. Sequellae of zinc deficiency are a leading cause of death among toddlers throughout the world; UNICEF estimates 450,000 deaths per year. Zinc deficiency also causes stunted development of the brains and the bodies of about 17-30% of all poor children in the US. Forty percent (21,000,000) of US school children are so poor they are given free lunch, and neither those free meals nor their habitual home meals contain much of the foods (red meat, shellfish) in which zinc is abundant. One of the main reasons that zinc deficiency goes untreated is that no one can diagnose it. To be sure, the signs of chronic, severe zinc deficiency can be recognized: stunted physical and mental development, open sores, loss of hair, infection proneness, fragile nails, and so on. But there is no good diagnostic test for early-stage, moderate (i.e., treatable) zinc deficiency. Serum zinc, in particular, like serum glucose, follows intake up and down in the short Figure 1. XRAY fluorescence term, over hours, but does not reflect zinc nutritional status. image of zinc in a fingernail clipping shows the uniformity We have solved the diagnostic problem. Abundant data indicate that of the zinc across the lateral the zinc content of fingernails is a sensitive and reliable indicator of zinc extent deficiency. Furthermore, though the zinc concentration of a nail will change along the longitudinal (proximo-distal) dimension if one makes lasting and substantial changes in zinc intake, the zinc concentration is relatively uniform in the lateral dimension (FIG 1) and from one finger to the next (FIG 2). Our proposed hand-held, field-portable, battery powered instrument will give the diagnostic measurement of fingernail zinc in 30-60 seconds with no inconvenience or discomfort to the subject. Using our diagnostic instrument, clinicians, aid workers, teachers, and others can go from village to village (or school to school) assessing the zinc nutritional status of 100s of children every day. Our instrument uses a miniature laser to make a brief ?spark? on the nail; the light emissions from that spark reveal the percent of zinc in the nail. This method (laser-induced-breakdown-spectroscopy, LIBS) is used in many applications, including the ?Chem Cam? that is mounted on the NASA Curiosity Rover on Mars. Besides the electricity for each measurement, there are no consumables. SIGNIFICANCE. The W.H.O., Gates Foundation, UNICEF, and the Copenhagen Consensus have all noted that zinc deficiency is 140 ppm a leading cause of death and stunted mental and physical 134 ppm 125 ppm development among toddlers, world wide. The Copenhagen Consensus have even identified dietary zinc supplementation as a leading cost-effective step to improve world health. INNOVATION. The use of LIBS to detect and quantify elements in solid media is not new, but the application of LIBS to nutritional (or toxicological) screening of people's tissues in situ is new, pioneered and patented (pending) by NeuroBioTex. While the concept is straightforward, the biology, optics, physics, and engineering are challenging. For example, incorporation of dietary zinc occurs at the growth plate, which is under the skin, between the cuticle and knuckle, so after a large and lasting increase in zinc intake, it takes about 60-90 days before the nail with elevated zinc emerges from under the cuticle. On the positive side, Figure 2/ Stability of zinc across 4 fingers and thumb is illustrated by King-Killilea atomic absorption laboratory data. Thumb and 4th finger omitted because different lengths and thus different growth eras. however, by measuring zinc along the proximo-distal length of the exposed nail, one can scan another 3-4 months of a subject's past zinc intake history. RESEARCH STRATEGY. We are partnering with some of the best laser and LIBS scientists and engineers in the world. In fact, we are opening a small NeuroBioTex facility within the Buildings of Ocean Optics, Inc. (OOi), which is adjacent to the U. C. Florida campus. This will insure that we can work closely with our UCF and OOi collaborators. The leaders in zinc nutrition, Janet King, Ananda Prasad, and Harold Sandstead will continue to guide the clinical, zinc deficiency diagnostic side of our research.
At least 17% of US toddlers suffer zinc deficiency; many of them die from it, and the survivors are stunted in brain growth, cognitive abilities, and body size. Our ZINC NUTIMETER will make it fast, easy, cheap, and routine to detect/diagnose this devastating condition before it kills or stunts the child. In turn, zinc supplement therapy can easily reverse the damage and save literally millions of children from debilitation each year.
| Fleming, David E B; Bennett, Stephen R; Frederickson, Christopher J (2018) Feasibility of measuring zinc in human nails using portable x-ray fluorescence. J Trace Elem Med Biol 50:609-614 |
