406
SIMPLIFIED PROCEDURE FOR FIELD PREPARATION OF HAIR D.N.A. SPECIMENS SIR,—There is a close association between the severity of malnutrition and decreased protein and D.N.A. content of hair-roots.1 This occurs because hair-roots atrophy under the stress of protein deprivation.2.3 It has been
suggested that public-health screening programmes might utilise this relationship by plucking hair samples from them to a populations under field conditions and posting laboratory for analysis of D.N.A. content.1 If this relationship is to be employed under tropical field conditions rather than in hospital, the effects of field chemical stabilisation and environmental temperatures must be assessed, because several weeks may pass between field sampling and laboratory analysis. We had the
opportunity to study these effects during a collaborative study. We epilated the samples under field conditions and posted them to a distant laboratory (about 3000 miles). The samples were exposed to environmental temperatures of 22-28 °C during the two-week period between epilation and analysis. Because differences in epilation and analytical techniques between investigators recent
affect the results, one investigator epilated and preall pared samples; the other analysed all samples using a numerical code to eliminate bias. Two techniques were compared. The first was the technique currently in hospital use. This method involved macerating the hair-roots in 1M NH40H in a mortar and the liquid sample to the laboratory pestle and transporting for D.N.A. analysis.1 The second technique was a simpler procedure which we felt was more appropriate for field use. It consisted in placing the hair-bulbs to be examined in file on the gummed surface of clear plastic tape to maintain them in position and then folding the gummed surface back over the roots to completely encase and protect them from contamination in transit. The sample was pressed firmly to exclude air; no other physical or chemical treatment was used. The samples were posted as ordinary letters without special handling precautions. In the laboratory the tape and roots were put into solution as a unit and then analysed as described previously.1 36 hair samples were epilated from the occipital area of 6 subjects on 6 occasions and placed directly in containers in the manner described previously.3 The samples were examined at 60 x the same day, and the anagen bulbs (growing phase) were separated for analysis. Telogens (resting phase) and broken hairs were discarded. Each sample was then divided at random into two subsamples of 10 anagens. The mean root diameter of each subsample was determined. One subsample was then macerated in 1M NH40H and the other placed on tape. Both subsamples were then posted to the central laboratory in the The data was examined by analysis of same packet. variance. in There were highly significant differences (P< 0-001) the D.N.A. content of hair-root specimens between the subsamples of the same individuals sampled at the same time. These differences were not caused by sample selection (i.e., variation in bulb size between subsamples) because there were no significant differences in mean bulb diameter between the populations of macerated and taped samples (P> 01). Neither were these results affected by differences in epilation technique, because only one pull was used to obtain the sample, and the two subsamples for each individual were formed by a random distribution of this sample. When we examined the total population of hairs we found that the D.N.A. content of the macerated samples was, on the average, only 40% that of the tape samples.
might
1. 2. 3.
Crounse, R. G., Bollet, A. J., Owens, S. Nature, 1970, 228, 465. Bradfield, R. B., Jelliffe, E. F. P. ibid. 1970, 225, 283. Bradfield, R. B. Am. J. clin. Nutr. 1972, 25, 720.
When we examined only hairs of the same root diameter we found the macerated samples varied from 20% to 90% of the respective tape values. Control samples taken on one day were posted on several different occasions. The values for the tape samples were uniform (±8%) and consistent with normal values. The values for the macerated samples varied from 40% to 100% of the tape values. This suggests solubility differences or sample loss in the macerated samples, although this was not noted at the time of analysis. Soluble-protein and D.N.A. content are a function of hairCrounse et al.1 reported a high correlation root size. between hair-root volume and soluble protein/root (r27 =0.90)(P < 0001) and also between soluble-protein and D.N.A. concentration (r112=0.92)(P< 0.001).1 In this study we confirmed this observation with the finding of a highly significant relationship between hair-root diameter and soluble protein/root (r27 ==0-72)(P < 0-001) and between root for adult diameter and D.N.A./root (r27=0.44)(P
SIMPLIFIED PROCEDURE FOR FIELD PREPARATION OF HAIR D.N.A. SPECIMENS SIR,—There is a close association between the severity of malnutrition and decreased protein and D.N.A. content of hair-roots.1 This occurs because hair-roots atrophy under the stress of protein deprivation.2.3 It has been
suggested that public-health screening programmes might utilise this relationship by plucking hair samples from them to a populations under field conditions and posting laboratory for analysis of D.N.A. content.1 If this relationship is to be employed under tropical field conditions rather than in hospital, the effects of field chemical stabilisation and environmental temperatures must be assessed, because several weeks may pass between field sampling and laboratory analysis. We had the
opportunity to study these effects during a collaborative study. We epilated the samples under field conditions and posted them to a distant laboratory (about 3000 miles). The samples were exposed to environmental temperatures of 22-28 °C during the two-week period between epilation and analysis. Because differences in epilation and analytical techniques between investigators recent
affect the results, one investigator epilated and preall pared samples; the other analysed all samples using a numerical code to eliminate bias. Two techniques were compared. The first was the technique currently in hospital use. This method involved macerating the hair-roots in 1M NH40H in a mortar and the liquid sample to the laboratory pestle and transporting for D.N.A. analysis.1 The second technique was a simpler procedure which we felt was more appropriate for field use. It consisted in placing the hair-bulbs to be examined in file on the gummed surface of clear plastic tape to maintain them in position and then folding the gummed surface back over the roots to completely encase and protect them from contamination in transit. The sample was pressed firmly to exclude air; no other physical or chemical treatment was used. The samples were posted as ordinary letters without special handling precautions. In the laboratory the tape and roots were put into solution as a unit and then analysed as described previously.1 36 hair samples were epilated from the occipital area of 6 subjects on 6 occasions and placed directly in containers in the manner described previously.3 The samples were examined at 60 x the same day, and the anagen bulbs (growing phase) were separated for analysis. Telogens (resting phase) and broken hairs were discarded. Each sample was then divided at random into two subsamples of 10 anagens. The mean root diameter of each subsample was determined. One subsample was then macerated in 1M NH40H and the other placed on tape. Both subsamples were then posted to the central laboratory in the The data was examined by analysis of same packet. variance. in There were highly significant differences (P< 0-001) the D.N.A. content of hair-root specimens between the subsamples of the same individuals sampled at the same time. These differences were not caused by sample selection (i.e., variation in bulb size between subsamples) because there were no significant differences in mean bulb diameter between the populations of macerated and taped samples (P> 01). Neither were these results affected by differences in epilation technique, because only one pull was used to obtain the sample, and the two subsamples for each individual were formed by a random distribution of this sample. When we examined the total population of hairs we found that the D.N.A. content of the macerated samples was, on the average, only 40% that of the tape samples.
might
1. 2. 3.
Crounse, R. G., Bollet, A. J., Owens, S. Nature, 1970, 228, 465. Bradfield, R. B., Jelliffe, E. F. P. ibid. 1970, 225, 283. Bradfield, R. B. Am. J. clin. Nutr. 1972, 25, 720.
When we examined only hairs of the same root diameter we found the macerated samples varied from 20% to 90% of the respective tape values. Control samples taken on one day were posted on several different occasions. The values for the tape samples were uniform (±8%) and consistent with normal values. The values for the macerated samples varied from 40% to 100% of the tape values. This suggests solubility differences or sample loss in the macerated samples, although this was not noted at the time of analysis. Soluble-protein and D.N.A. content are a function of hairCrounse et al.1 reported a high correlation root size. between hair-root volume and soluble protein/root (r27 =0.90)(P < 0001) and also between soluble-protein and D.N.A. concentration (r112=0.92)(P< 0.001).1 In this study we confirmed this observation with the finding of a highly significant relationship between hair-root diameter and soluble protein/root (r27 ==0-72)(P < 0-001) and between root for adult diameter and D.N.A./root (r27=0.44)(P
