91-102 (March/April 2001)
Skin optics revisited by in vivo confocal microscopy:
Melanin and sun exposure
PIERRE CORCUFF, CEŽ LINE CHAUSSEPIED, GENEVIE`VE MADRY,
and CHRISTOPHE HADJUR, L'OreŽal Recherche, Laboratoires de Recherche
AvanceŽe, 93601 Aulnay-sous-bois, France. Accepted for publication
February 28, 2001. Presented at the XXIth International IFSCC
Congress, Berlin, 2000.
Synopsis
A new confocal prototype dedicated to the exploration of in
vivo human skin has been constructed around a laser confocal
module (Oz Noran, Inc.) and a skin contact device, assuring
perfect stability of skin images. The power of the Argon/Krypton
laser source has been limited to 2mW to secure safety, and the
laser provides three visible wavelengths: 488, 568, and 647
nm. Optical sections were digitized at video rate, providing
easy and rapid measurements of the thickness of epidermal layers
and time-resolved information. Unexpected details of the epidermis
were recorded with the blue laser line. Melanin provided strong
reflection of the basal keratinocytes instead of the absorption
expected. The 3D reconstruction of the melanin cap in basal
keratinocytes confirmed the behavior of melanosomes acting as
myriads of nanomirrors that reflected light. Confocal images
of the posterior aspect of the forearm were recorded before
sun exposure and then for one month after exposure. There was
a 25% increase in the thickness of the stratum corneum. Bright
inclusions into the dark nucleus of numerous spinous cells were
interpreted as local condensation of chromatin. Numerous bright
intercellular filaments were attributed to melanosomes filling
up dendrites of melanocytes. A striking observation concerned
the lack of melanosome caps in basal keratinocytes. In vivo
confocal microscopy affords new insight to the role of melanin
and its gradual migration after sun exposure.
52, 103-118 (March/April 2001)
Ultraviolet damage on natural gray hair and
its photoprotection
TAO GAO and ANN BEDELL, Croda Inc., North American Technical
Center, 180 Northfield Avenue, Edison, NJ 08837. Accepted for
publication February 28, 2001.
Synopsis
The physicochemical properties of natural gray hair obtained
from the heads of individuals and as well as commercial samples
were investigated. No statistically significant differences
were observed in terms of their central maximum diameter, central
cross-sectional area, central ellipticity, average tensile strength,
and average extent of transverse swelling between gray and black
hair. The correlation between the elongation and the contraction
of the cross-sectional area of hair fibers during extension
was established as a statistically linear function, with a coefficient
of 0.758. The damage on natural gray hair from ultraviolet (UV)
irradiation were assessed by measuring the following parameters:
hair color, Young's modulus, stress-tobreak, wet combing force,
dynamic advancing contact angle, tryptophan damage, cuticle
abrasion, and transverse swelling of hair fiber in 0.1 N NaOH
solution. It has been found that gray hair undergoes more severe
UV damage and needs more UV protection than dark brown hair.
Experimental results indicate that the quaternized UV absorber,
cinnamidopropyltrimonium chloride (CATC), delivered from a simple
shampoo system, is more substantive on hair and more effective
in protecting hair from UV damage than a conventional UV filter.
CATC also provided an additional conditioning benefit on hair.
52, 119-129 (March/April 2001)
Examining cationic polysaccharide deposition
onto keratin surfaces through biopolymer fluorescent labeling
JAMES V. GRUBER, FRANCOISE M. WINNIK, ANDRE LAPIERRE, NEELA
D. KHALOO, NIRAJ JOSHI, and PETER N. KONISH, Amerchol Corporation,
136 Talmadge Rd., Edison, NJ 08818-4051 (J.V.G., N.J., P.N.K),
and Department of Chemistry, McMaster University, 1280 Main
Street West, Hamilton, Ontario, Canada L8S 4M1 (F.M.W., A.L.,
N.D.K.). Accepted for publication February 28, 2001.
Synopsis
Fluorescein-labeled polyquaternium-10 and guar hydroxypropyltrimonium
chloride were employed to study the deposition behavior of these
cationic polymers onto hair from a surfactant system. The influence
of the covalently attached fluorescein dye on labeled polyquaternium-10
was examined through rheological studies and comparative studies
against data previously obtained from radiolabeled polyquaternium-10.
A quantitative method for analyzing the amount of cationic polymer
that deposits onto hair during a standard shampooing process
has been developed using the labeled cationic polymers. The
technique requires digestion of the hair and analysis of the
resulting solutions against known standardization curves. It
has been found that the molecular weight of the cationic polymers
plays the most significant role in influencing the deposition
of the polymers from surfactant, a far greater role than either
cationic charge or washing cycles. The technique also allows
for determination of polymer deposition at various tress locations,
allowing for the study of the influence of tress age (i.e.,
damage) on polymer deposition. The use of fluorescein-labeled
polyquaternium-10 also provides a unique opportunity to visualize
the deposited polymers on individual hair fibers via fluorescent
or confocal microscopy.
52, 131-136 (March/April 2001)
The use of x-ray fluorescent spectroscopy to
study the influence of cationic polymers on silicone oil deposition
from shampoo
JAMES V. GRUBER, BURTON R. LAMOUREUX, NIRAJ JOSHI, and LUIS
MORAL, Amerchol Corporation, 136 Talmadge Rd., Edison, NJ 08818-4051
(J.V.G., N.J., L.M. [retired]), and Union Carbide Corporation,
1 River Rd., Bound Brook, NJ 08876 (B.R.L.). Accepted for publication
February 28, 2001.
Synopsis
In this study, x-ray fluorescent spectroscopy was employed,
in a non-destructive way, to analyze the influence that water-soluble,
cationic hydroxyethylcellulose (i.e., polyquaternium-10) has
on the deposition of silicone oil (dimethicone) onto hair. Virgin
brown hair tresses were washed with various model shampoos that
contained emulsified dimethicone. The shampoos were modified
only by the addition or absence of polyquaternium-10. The results
indicate that the cationic polymers do influence silicone oil
deposition onto hair during the shampooing process. In the absence
of cationic polymer, the silicone oils deposit readily, but
appear to show "build-up" phenomena upon repeated washings.
When a cationic polymer is present in the continuous phase of
the shampoo, the build-up phenomena is significantly diminished,
and silicone oil deposition remains relatively constant in repeated
washings. In addition, we have noted that the molecular weight
of the cationic polymer can have a strong effect on silicone
oil deposition. It appears that the higher the molecular weight
of the polyquaternium-10, the greater the amount of silicone
deposition onto the surface of the hair. To demonstrate that
the analysis technique has potential applications in commercial
shampoos, we examined a commercial "2-in-1" shampoo that contains
dimethicone and polyquaternium-10 and found that the data for
our simple model shampoos and the commercial shampoo correlated
closely.
52, 137-154 (March/April 2001)
Papers Presented at the 2000 Annual Scientific Meeting (Friday's
Program) December 7-8, 2000 New York Hilton New York, NY
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