Main

The existence of a ring at a spacing of 4.5 nm was first attributed to ‘lipid crystals’2 that could be removed only by prolonged extraction in hot solvents. Our experience3,4 and that of our colleagues from l'Oréal5 confirms the presence of intense diffraction ring(s) arising from lipids in keratinous tissues. We recently performed a microdiffraction analysis on beamline ID13 at the ESRF and observed in human hair and other tissues that the lipid granules are mainly located in the outer part of the tissue6. We are therefore unable to explain the lack of the ring at 4.5 nm in the diffraction pattern of normal hair reported by James et al. One possibility is that working with a microbeam inhibited the observation of the ring because the lipid granules took up unfavourable orientations.

To compare X-ray diffraction patterns of hair from healthy subjects and breast-cancer patients under the same experimental conditions, we conducted experiments at station D43 of the synchrotron source LURE (Université Paris-Sud). We compared diffraction patterns of scalp hair from ten supposedly healthy people (seven females and three males) with the patterns from ten breast-cancer patients (all female). We irradiated a bundle of hair in a glass capillary with a 0.5-mm monochromatic X-ray beam. The diffraction patterns from healthy subjects displayed an intense ring at 4.48±0.05 nm. The variability of the patterns from breast-cancer patients was larger, but the ring was intense for one patient, of low intensity for seven others, and not observable for the remaining two.

Our observations differ from those of James et al. in two main respects. First, we observed the diffraction ring at 4.5 nm on patterns from all healthy subjects (100%, against 22% by James et al.). Second, the ring is present in eight out of ten patterns from breast-cancer patients (instead of the 100% observed by James et al.). This conclusion is illustrated in Fig. 1 : in two out of ten cases, our split patterns between healthy and breast-cancer subjects are exactly the opposite of that of James et al. However, it should be remembered that the studies used different hair types.

Figure 1: Split X-ray diffraction pattern.
figure 1

Left, scalp hair from healthy subject, displaying intense rings arising from lipid granules; right, hair from breastcancer patient, with no clear rings.

Full size image

Editorial noteFull experimental details of the work by James et al. have been published1,2. Detailed set-ups for the three different beamlines and links are available from http://www.ansto.gov.au/natfac/asrp.html

1.Wilk, K. E., James, V. J. & Amemiya, Y. Biochim. Biophys. Acta 1245, 392-396 (1995). 2.James, V. J., Wilk, K. E., McConnell, J. F. & Baranov, E. P. Int. J. Biol. Macromol. 17, 99-104 (1995).