Rate of Hair Growth

Saitoh, Masafumi; Uzuka, Makoto; Sakamoto, Masako; Kobori, T.

doi:10.1007/978-3-642-49735-3_353

Cited by 91 publications

(106 citation statements)

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“…Hair grows at the rate of about 1 cm per month (Saitoh et al 1969), so the samples we analysed represented about 6 months' growth. Faecal samples were dried, homogenised and ground.…”

Section: Methodsmentioning

confidence: 99%

Diets of impala from Kruger National Park: evidence from stable carbon isotopes

Sponheimer

Grant

Ruiter

et al. 2003

Koedoe

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Impala are known to exhibit dietary flexibility, relying primarily on browse in some areas and graze in others. In this study we use stable isotope analysis of faeces and hair to examine the diets of impala in Kruger National Park. As expected, the data show that impala are mixed-feeders and highly distinct from grazing buffalo and browsing kudu. Moreover, impala, buffalo, and kudu faeces contain 2.1 %, 1.4 %, and 2.9 % nitrogen respectively, suggesting that impala diets are of intermediate quality. There are also marked differences between impala populations in the northern and southern regions of the park. The northern impala graze less than their southern counterparts. This difference probably reflects decreased availability of herbaceous forage in the mopane-dominated north. Males and females also have different diets, with males grazing more than females.

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“…Hair grows at the rate of about 1 cm per month (Saitoh et al 1969), so the samples we analysed represented about 6 months' growth. Faecal samples were dried, homogenised and ground.…”

Section: Methodsmentioning

confidence: 99%

Diets of impala from Kruger National Park: evidence from stable carbon isotopes

Sponheimer

Grant

Ruiter

et al. 2003

Koedoe

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“…3 Because of the balance existing between serum levels and hair concentration, measurement of endogenously produced hormonal levels in hair may reflect average hormone levels over months. Specifically, because hair grows approximately 1 centimeter per month (range 0.6-1.4 cm) 4 , a hair sample of 2-3 cm reflects average hormone levels over the previous 2-3 months. Hence, unlike other matrices, hair cortisol may represent long-term exposure to the hormone.…”

mentioning

confidence: 99%

Measurement of cortisol in human Hair as a biomarker of systemic exposure

Sauvé

Koren²,

Walsh³

et al. 2007

CIM

486

395

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Clin Invest Med 2007; 30 (5): E183-E191. AbstractPurpose: Current methods for measuring long-term endogenous production of cortisol can be challenging due to the need to take multiple urine, saliva or serum samples. Hair grows approximately 1 centimeter per month, and hair analysis accurately reflects exposure to drug abuse and environmental toxins. Here we describe a new assay for measurement of cortisol in hair, and determined a reference range for non-obese subjects. Methods: For measurement of cortisol in hair we modified an immunoassay originally developed for measuring cortisol in saliva. We compared hair samples obtained from various parts of the head, and assessed the effect of hair dying. We analyzed hair samples from non-obese subjects, in whom we also obtained urine, saliva and blood samples for cortisol measurements. Results: The mean extraction recovery for hair cortisol standards of 100 ng/ml, 50 ng/ml and 2 ng/ml (n=6) was 87.9%, 88.9% and 87.4%, respectively. Hair cortisol levels were not affected by hair color or by dying hair samples after they were obtained. Cortisol levels were decreased in hair that was artificially colored before taking the sample. The coefficient of variation was high for cortisol levels in hair from different sections of the head (30.5%), but was smaller when comparing between hair samples obtained from the vertex posterior (15.6%). The reference range for cortisol in hair was 17.7-153.2 pg/mg of hair (median 46.1 pg/mg). Hair cortisol levels correlated significantly with cortisol in 24-hour urine (r=0.33; P=0.041). Conclusion:The correlation of hair cortisol with 24-hour urine cortisol supports its relevance as biomarker for longterm exposure.Cortisol is a glucocorticoid hormone produced by the adrenal glands. In humans, cortisol levels are increased in severe stress, depression, and selected systemic diseases such as Cushing's syndrome. Proper assessment of endogenous cortisol secretion is required to adequately determine its relation to these clinical conditions. For that end, cortisol is currently measured in saliva, serum and urine. While each of these measurements has advantages and limitations, all these methods require multiple samples to provide an assessment of cortisol levels over prolonged periods of time. Furthermore, due to diurnal variations

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“…Because the rate of hair growth in adults is about 1 cm per month, the time and duration of exposure can be obtained by cutting the hair into segments [29]. 3-4 cm of hair growth may suggest drug ingestion for at least 3-4 months prior to testing in adults.…”

Section: Discussionmentioning

confidence: 99%

Neonatal Hair Analysis for Benzoylecgonine: A Sensitive and Semiquantitative Biological Marker for Chronic Gestational Cocaine Exposure

Katikaneni

Salle²,

Hulsey³

2002

Neonatology

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Hair analysis for the major metabolite of cocaine, benzoylecgonine (BZE) was performed in a cohort of 251 predominantly African-American newborns utilizing a modified radioimmunoassay (RIA) (Abuscreen Roche Laboratories, Nutley, N.J., USA). Maternal drug intake was confirmed by positive urine drug screen for cocaine metabolites at the time of delivery. The BZE concentrations reported here are the composites of both the parent compound cocaine (hydrolyzed to BZE) and the native BZE metabolized by the patient and deposited in the hair follicle. Hair analysis as an indicator for gestational cocaine exposure had a sensitivity of 88%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 85%. The range of BZE was 99–23,300 ng/g of hair, with 79% having hair BZE levels <5,000 ng/g of hair. The BZE RIA was confirmed by gas chromatography and mass spectrometry (GC/MS). Of the 18 mother/infant pairs tested, the hair BZE ratio (maternal to neonatal) varied from 0.5 to 8.9 in 13 pairs. In spite of maternal high hair BZE levels, 5 newborns had no evidence of hair BZE, stressing the importance of the placental role for the cocaine transfer to the fetus. After controlling for gestational age, higher BZE levels significantly correlated with smaller head circumference (p < 0.03) and birth weight (p < 0.01).

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Rate of Hair Growth

Cited by 91 publications

References 0 publications

Diets of impala from Kruger National Park: evidence from stable carbon isotopes

Diets of impala from Kruger National Park: evidence from stable carbon isotopes

Measurement of cortisol in human Hair as a biomarker of systemic exposure

Neonatal Hair Analysis for Benzoylecgonine: A Sensitive and Semiquantitative Biological Marker for Chronic Gestational Cocaine Exposure

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