Prenatal hairs

DNA sequences as short as 50-100 bp and as long as 10 kb can be amplified. Twenty cycles provide an amplification of 10 and 30 cycles of 10. The PCR allows the DNA in a single cell, hair follicle, or spermatozoon to be amplified and analyzed. Thus, the applications of PCR to forensic medicine are obvious. The PCR is also used (1) to detect Infectious agents, especially latent viruses (2) to make prenatal genetic diagnoses (3) to detect allelic polymorphisms (4) to establish precise tissue types for transplants and (5) to study... 

On replication, insertion or deletion of bases may occur. Chain scission and chromosome breaks are also possible. Quinacrine is useful in human cytogenetics, since it intercalates significantly into the heterochromatin of the Y chromosome, making it fluoresce and rendering it identifiable cytologically. Detection of the Y chromosome is important in prenatal sex determination. Other dyes present in our environment are potentially mutagenic. For example, some hair dyes were shown to be mutagenic for E. coli. 

Human pharmacokinetic studies indicate that methylmercury has a half-life in blood and the whole body of about 50 days (CDC 2005). Hair grows at about 1 cm/month with a delay of around 20 days between current blood concentration and appearance of mercury in hair (Myers et al. 2003). Thus, postnatal maternal hair can be analyzed sequentially to evaluate timing of methylmercury exposure during pregnancy. However, the potential that this affords to document critical periods of prenatal methylmercury exposure has yet to be realized. 

On the basis of maternal hair concentration, the third study (conducted in the Seychelles) did not find any association between prenatal methylmercury exposure and adverse neuro-psychologic effects (Myers et al. 2003). Reasons for the discrepancies are not known but have been suggested to include differences in the child s age at testing, genetic susceptibilities of the populations, patterns of exposure (episodic vs continuous), and coexposure to polychlorinated biphenyls in the Faroes but not Seychelles populations (Rice et al. 2003). 

C. Cox, T.W. Clarkson, D.O. Marsh, L. Amin-Zaki, S. Tikriti, and G.G. Myers, Dose-response analysis of infants prenatally exposed to methyl mercury An application of a single compartment model to single strand hair analysis. Environ. Res. 49 318, 1989. 

Biomarkers do not measure exposure directly, but are an indicator of absorbed dose. A biomarker of exposure is defined as a xenobiotic substance or its metabolite(s) or the product of an interaction between a xenobiotic agent and some target molecules(s) or cell(s) that is measured within a compartment of an organism and can be related to exposure. Urine, blood, nail, saliva, hair, and faeces are common media collected for biomarker measurements. Maternal biomarkers of exposure can also be measured in amniotic fluid and breast milk. These matrices can also provide a measure of exposure for children, both prenatally and postnatally. Biomarkers in first teeth have also been used to assess early childhood exposure, whereas biomarkers in meconium and cord blood have been used to assess in utero exposures. Biomarkers of genetic damage (e.g. DNA adducts) have been extensively used to assess exposure to genotoxic agents (Neri et al., 2006). 

In a blind study with the same research group, but in an everyday clinical prenatal setting, the detection efficiency of hair analysis was compared to that of urinalysis." The results of this study showed that the detection of maternal cocaine use by urinalysis, applied at the first prenatal visit, was only 26% that of hair analysis. 

It is also interesting to note that cocaine can be determined in amniotic fluid, cord blood, infant urine, meconium, and maternal hair to detect prenatal cocaine use [101]. GC-MS was performed after an appropriate extraction procedure and 51 of 115... 

Myers et al. (1997) evaluated the population of the SCDS for developmental milestones similar to those determined in Iraq. As part of this ongoing study, cohort children were evaluated at 6.5, 19, 29, and 66 months of age. At 19 months care-givers were asked at what age the child walked (n=720 out of 738) and talked (n=680). Prenatal mercury exposure was determined by atomic absorption analysis of maternal hair segments corresponding to hair growth during the pregnancy. 

There are differences in the outcomes of these epidemiology studies on low level chronic exposures to methylmercury in foods. Davidson et al. (1998) report no adverse developmental effects associated with prenatal and postnatal exposure to methylmercury in fish in a Seychelles Island cohort of children at age 66 months (n=708). The exposure levels are reflected in maternal hair levels of 6.8 ppm for the prenatal exposure (SD=4.5, n=711) and children s hair levels of 6.5 ppm (SD=3.3, n=708) for both the prenatal and subsequent postnatal exposure. The age-appropriate main outcome measures included (1) the... 

The 66-month study of 711 children in the Seychelles islands assessed the effects of prenatal MeHg in tests of global intelligence and developmental milestones. No adverse effects were seen that could be attributed to MeHg. Maternal hair samples collected at birth contained Hg concentrations that ranged from 0.5 to 27 ppm (mean, 6.8 ppm). Meanwhile,... 

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