V Pecoraro’s research while affiliated with National University of Rosario and other places

... As expected, none of the variables, total hair density, %T and diameter seem affected by age [6,12,13,[17][18][19] since the age-range adopted here (18-35y) was limited. However, a gross bi-modal clustering of the global population indicates that hair growth rate slightly decreases (by 0.4 cm/year, p<0.001) above 26y, as compared to below 25y, all scalp areas and gender included. ...

Reference:

Diversity in human hair growth, diameter, colour and shape. An in vivo study on young adults from 24 different ethnic groups observed in the five continents

... Hair analysis is a promising method for TDM because it allows the measurement of drug exposure over a longer period of time: drugs and their metabolites can become incorporated into the hair as it grows and thus provide a historical record of drug exposure. In this respect, segmental hair analysis allows an assessment of monthly drug exposure because hair grows by approximately 1 cm per month (Pecoraro et al., 1990;LeBeau et al., 2011). Although hair analysis has been used for TDM of several drugs [including antiretrovirals, antituberculosis drugs, antiepileptics and antipsychotics (Williams et al., 2001;Gandhi et al., 2011;van Zyl et al., 2011;Liu et al., 2014;Baxi et al., 2015;Gandhi et al., 2019;Metcalfe et al., 2019;Sun et al., 2019)], there are challenges in the application to asthma patients; the doses of inhaled drugs are low (with tens to hundreds of micrograms), as is the systemic bioavailability of the active compounds (Winkler et al., 2004). ...

Reference:

Therapeutic drug monitoring of corticosteroids/β2-agonists in the hair of patients with asthma: an open-label feasibility study

... He stated that the average was 15% in telogen and 5% in anagen. Fleck and Fleck [12] , wiitzel and Braun-Falco [13] , Kligman [3] , and Pecoraro et al. [14] then determined the proportion of each of these phases to the full growth cycle of adult and newborn scalp hair. ...

Reference:

Synthesizing of nanoparticles by human hair in alcohol base with effect of potentization

... 11,38 Furthermore, Barth and Pecoraro et al. reported higher HGRs in male vs. female children (5-15% faster hair growth; 340 vs. 302 μm/day, respectively), but both examined small sample sizes and only performed descriptive statistical analyses. 38,45 On the whole, adult hair studies provide biomarker research with more sophisticated findings (more studies, larger sample sizes, rigorous methodologies, and statistical analyses) than child hair studies. For example, while the composition of adult hair is known (0.25-0.95% trace elements,1-9% lipids, 3-5% endogenous water, and 65-95% protein), 46-50 the composition of children's hair largely remains unknown. ...

Reference:

Linear hair growth rates in preschool children

... Prior to lab analysis, individual's hair samples were randomly ordered and segmented for a total of four 3 cm hair segments per individual. Given that the average hair growth in humans is approximately one centimeter per month (Astore, Pecoraro, & Pecoraro, 1979;Barman, Astore, & Pecoraro, 1965;Barth, 1986;Loussouarn, El Rawadi, & Genain, 2005;Pecoraro, Astore, & Barman, 1969), the four hair segments reflected the following time periods: preconception (3-6 cm from the scalp at enrollment), 1st trimester (3 cm from the scalp at enrollment), 2nd trimester (3-6 cm from the scalp at delivery), and 3rd trimester (3 cm from the scalp at delivery) ( Figure 1). Segments further from the scalp were excluded due to concerns of measurement error from cortisol degradation and washout (Hamel et al., 2011;Li et al., 2012;Russell, Koren, Rieder, & Van Uum, 2012;. ...

Reference:

Stress and hair cortisol concentrations from preconception to the third trimester

... The axillary hair density is believed to vary according to gender, ethnicity, age and hormonal status, but published data are scarce on the hair parameters of this region in normal individuals. 8 In two patients in whom no axillary hair was observed on dermoscopy examination, it was not possible to determine whether this was due to hormonal or AFF status. Hence, it is hard to draw conclusions in studies of axillary alopecia without a carefully matched control group. ...

Reference:

Dermoscopy findings of the axilla of women with frontal fibrosing alopecia

... Although currently there is much excellent literature on androgenetic alopecia (8,(31)(32)(33)(34) we do not know the underlying cellular basis for the intrafollicular changes that occur. Many authors consider that androgenetic alopecia, and the process of follicle miniaturization is a normal biological phenomenon (35)(36)(37); others believe it to be a disease (38). In either case, hormonal influences almost certainly act by modulating the intrinsic dermal-epidermal interactions that control all core aspects of follicle activity. ...

Reference:

Cellular and developmental aspects of androgenetic alopecia

... Given the high percentage of HFs remaining in anagen for years (Halloy et al., 2000;, human scalp skin is energetically expensive; only the balding scalp (with its characteristic HF miniaturisation process) becomes more economical. Perhaps the higher energy-efficiency of this hair phenotype is related to the purported trend of the human species towards progressive balding (Barman et al., 1967;Kushlan, 1985;Dawber, 1997). ...

Reference:

Resting no more: Re-defining telogen, the maintenance stage of the hair growth cycle

... The current study confirms previous research regarding an average scalp hair growth rate of about 10 mm per month. Growth rate has generally been studied in regrown hairs previously shaved or clipped, with a follow up of a few days to a fortnight, which also allowed for identification of growing and resting hair follicles at a certain time-point 35,36 . With a longer follow up time, of weeks to months, the impact of hair follicles switching between growing, transitioning and resting phases (anagen, catagen and telogen) on the total hair growth should be detectable and influence the individual lengths of regrown hairs within a sampling area. ...

Reference:

Segmental hair analysis as a retrospective testosterone diary: possibilities and pitfalls

... 7 However, decreases in the proportion of thin hair with age have rarely been reported. 6 This finding may be explained by the slower metabolic processes associated with age, 8 leading to a reduction in the duration of growth phases and prolongation of the latency period: thin hair renewal is reduced, so the proportion of thick hair increases. 6 The significant reduction in break stress in the oldest group reflected a weakening of the hair fibres after 70 years of age. ...

Reference:

Quantitative and physical characterization of normal hair ageing in White European women: a single‐centre study