bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Allele and Haplotype Diversity Across 25 Genomic Regions in Three Eastern European Populations
Authors: Khrunin Andrey , Mihailov Evelin , Nikopensius Tiit , Krjutškov Kaarel , Limborska Svetlana , Metspalu Andres
Published: April 2009

Objective: Individual population history is the main reason for the variability of linkage disequilibrium (LD) patterns and haplotype frequencies among populations. Such diversity may influence the transferability of tag SNPs from one population to another. Our goal was to compare patterns of pairwise LD and allele and haplotype frequencies in Estonian and Russian populations, to estimate the genetic variation between populations and assess the potential transferability of tag SNPs. Methods: 452 SNPs from 25 unlinked genomic regions on 12 chromosomes were genotyped in 140 Estonians and 207 Russians from Northern and Western regions of the European area of Russia. Results: The allele frequency distributions were highly consistent between populations (R > 0.90 for all pairwise comparisons). The overall frequency variation among populations was low (FST = 0.0054). The number of SNPs with high-range FST values (0.02–0.09) was most prominent for the MC5R genomic region. Haplotype heterogeneity among populations was low (FST values ranged within 0.00–0.01, with the exception of haploblocks in the ADIPOR2 and MC5R regions). The interpopulation proximity was also evaluated using haplotype diversity. Conclusion: Our data showed a high concordance between the populations studied, which may be considered as the result of their historical formation on a cognate genetic basis.
Effects of Losartan Pretreatment in an Experimental Model of Ischemic Acute Kidney Injury
Authors: Molinas Sara M. , Cortés-González Cesar , González-Bobadilla Yvett , Monasterolo Liliana A. , Cruz Cristino , Elías María M. , Bobadilla Norma A. , Trumper Laura
Published: April 2009

Background/Aims: Contributions to the understanding of acute renal failure (ARF) pathogenesis have not been translated into an effective clinical therapy. We studied the effects of pretreatment with the angiotensin II type 1 (AT1) receptor blocker, losartan, on renal function, tissue injury, inflammatory response and serum aldosterone levels in a model of ischemic ARF. Methods: Rats underwent unilateral renal ischemia followed by 24 h of reperfusion (IR), and were pretreated or not with 8 (IRL8) or 80 (IRL80) mg/kg/day of losartan for 3 days. Results: IR kidneys showed marked renal dysfunction, epithelial damage, capillary congestion, increased myeloperoxidase (MPO) activity and increased TNF-α, IL1-β and IL-6 mRNA levels. IRL80 kidneys showed protection against dysfunction and tissue injury, associated with normal MPO activity and cytokine mRNA levels. The lower dose was not able to achieve the same degree of functional renoprotection and could not prevent an increase of MPO or proinflammatory cytokine mRNA levels. The high losartan dose completely prevented an increase of serum aldosterone levels induced by IR. Conclusion: Renoprotection of the high losartan dose would be mainly mediated by its anti-inflammatory actions. Our results show a potential pathophysiological role of AT1 activation in promoting renal dysfunction, structural injury, inflammation and aldosterone elevation after IR injury.
Effect of Chronic Antioxidant Therapy with Superoxide Dismutase-Mimetic Drug, Tempol, on Progression of Renal Disease in Rats with Renal Mass Reduction
Authors: Quiroz Yasmir , Ferrebuz Atilio , Vaziri Nosratola D. , Rodriguez-Iturbe Bernardo
Published: April 2009

Oxidative stress and inflammation play a major role in the progression of renal damage and antioxidants are potentially useful therapeutic options in chronic renal disease. We investigated if treatment with tempol, a superoxide dismutase mimetic that has beneficial effects in several experimental models of hypertension and acute kidney injury, ameliorates the chronic renal damage resulting in renal mass reduction. Rats with surgical 5/6 nephrectomy were randomly assigned to receive no treatment (CRF group, n = 10) or tempol, 1 mmol/l in the drinking water (CRF-tempol group, n = 10). Sham-operated rats (n = 10) served as controls. All rats were followed for 12 weeks post-nephrectomy. Tempol treatment reduced plasma malondialdehyde (MDA) levels and halved the number of superoxide-positive cells in the remnant kidney; however, the number of hydrogen peroxide-positive cells increased and the overall renal oxidative stress (MDA and nitrotyrosine abundance) and inflammation (interstitial p65 NF-κB, macrophage and lymphocyte infiltration) were unchanged. Proteinuria, renal function and glomerular and tubulointerstitial damage in the remnant kidney were similar in the CRF and CRF-tempol groups. In conclusion, tempol administration, at the dose used in these studies, decreased plasma MDA and heightened superoxide dismutation in the kidney, but was incapable of reducing renal oxidative stress or improving renal function or structure in the remnant kidney model.
Biological Activity of Retinoids Correlates with Affinity for Nuclear Receptors but Not for Cytosolic Binding Protein
Authors: Darmon Michel , Rocher Marie , Cavey Marie-Thérêse , Martin Bernard , Rabilloud Thierry , Delescluse Chantal , Shroot Braham
Published: April 2009

In order to better understand the respective roles of the nuclear retinoic acid receptors (RARs) and the cytosolic retinoic acid binding protein (CRABP) in the mode of action of retinoic acid (RA), several types of RA analogs have been synthesized. Representative compounds have been radiolabeled to a high specific activity and their binding (direct and competition) to RARs and CRABP was determined. Their biological activity on F9 embryonal carcinoma cell differentiation has been determined by a quantitative assay of plasminogen activator (PA). All biologically active analogs studied in this work bound to RARs. A good correlation was found between PA induction and affinity for the RARs, with the exception of RA itself which was a good ligand but a moderate inducer of F9 differentiation. Two biologically active analogs (compounds II and III) did not bind to the CRABP. One biologically inactive analog (compound VIII) bound to CRABP. These results strongly suggest that retinoids must bind to RARs but not necessarily to CRABP in order to induce cell differentiation in F9 cells.
Eicosanoid Release in Polymorphous Light Eruption: Selective UV-A-Induced LTB4 Generation by Peripheral Blood Leukocytes
Authors: Ruzicka Thomas , Przybilla Bernhard
Published: April 2009

The biochemical basis of ultraviolet-induced cutaneous inflammation in polymorphous light eruption (PLE) is not known. We investigated the potential role of eicosa-noids – derivatives of arachidonic acid – as mediators of inflammation in this common disorder. 13 patients were investigated, in whom skin lesions could be experimentally reproduced by repeated UV-A but not UV-B irradiation. Peripheral blood leukocytes of these patients were irradiated with UV-A or UV-B, and the release of leukotriene B4 (LTB4), LTC4 and prostaglandin E2 (PGE2) was measured. Cells from PLE patients, but not healthy controls, released selectively high amounts of LTB4 in response to UV-A. The UV-A-induced LTB4 release was light-dose-dependent. This phenomenon was not observed with UV-B. The selective UV-A-induced release of LTB4 could play a major role in the pathophysiology of cutaneous inflammation in PLE.
Skin Metabolism and Transdermal Absorption of Viprostol, a Synthetic PGE2 Analog, in the Rat: Effect of Vehicle
Authors: Nicolau G. , Dahlin D.C. , Kohlbrenner M. , Chan P.S. , Ronsberg M.A , Saunders T.K. , Yacobi A. , Cervoni P.
Published: April 2009

The effects of three formulations on the transdermal absorption and antihypertensive activity of 14C-viprostol were investigated in the spontaneously hypertensive rat. Single doses of 14C-viprostol were administered topically to rats in three formulations: silicone oil, petrolatum base, and triethyl citrate (TEC). Mean arterial blood pressure (MABP) and blood concentrations of radioactivity were measured over 24 h. Metabolic profiles in the skin were determined by HPLC; in vitro skin metabolism was also investigated. Following topical dosing with 14C-viprostol in petrolatum and silicone oil, substantial systemic concentrations of radioactivity and decreases in MABP were observed. In contrast, administration of 14C-viprostol in TEC led to negligible blood concentrations of radioactivity and the lowering of MABP was diminished. Metabolic profiles in skin at the application site from rats dosed with viprostol in petrolatum and silicone oil indicated rapid hydrolysis of the viprostol methyl ester to the active free acid, CL 115,129. When TEC was used as the dosing vehicle, the conversion of viprostol to the free acid appeared to be slower. TEC (an ester itself) was also found to reduce the rate of hydrolysis of viprostol in rat skin 10,000-g supernatants.
Effect of Lonapalene on Metabolism of Exogenous Arachidonic Acid in Human Platelets
Authors: Gibert C. , Vila L. , Puig L. , Solá J. , Moragas J.M.
Published: April 2009

Lonapalene was studied as a topical antipsoriatic agent on the basis of its inhibitory effect on 5-lipoxygenase. We studied the effect of lonapalene on the metabolism of exogenous arachidonic acid in washed platelet suspensions by RP-HPLC. Lonapalene was shown to inhibit platelet cyclooxygenase, with substrate diversion towards 12-HETE production. The pattern of inhibition was similar to that of indometacin, although lonapalene was about 1,000 times weaker. The dual inhibition of lonapalene and concomitant deviation of arachidonic acid metabolism may have potential implications, with regard to therapeutic indications and side effects, which deserve further study.
Pharmacological Modulation by Cetirizine and Atropine of the Histamine- and Methacholine-Induced Wheals and Flares in Human Skin
Authors: Van Neste D. , Ghys L. , Antoine J.L. , Rihoux J.P.
Published: April 2009

This study was planned to verify whether different methods for the measurement of skin reactivity, i.e. wheal and flare area, wheal thickness, skin capacitance and transepidermal water loss, were or were not able to discriminate between intradermally injected agonists (histamine and methacholine). For evaluating agonist/antagonist interactions, we adopted a cross-over, double-blind, placebo-controlled study designed to compare the effects of cetirizine and atropine. The intradermal injection of agonists elicited the appearance of wheal and flare reactions and, after histamine, the skinfold thickness was significantly increased. Skin capacitance and transepidermal water loss measurements reflected sweat gland activation after methacholine injection but were, respectively, not or less affected by histamine dry skin prick test or saline; hence, both methods appear very sensitive for in vivo testing of cholinomimetic agents. Cetirizine inhibited all the specific skin modifications induced by histamine challenge, wheals, flares and increased thickness, without affecting the methacholine-induced perspiration. This would further support the H1 specificity of this anti-H1 agent in vivo. However, at the agonist/antagonist ratios tested in view of the safety of the test persons, we were unable to objectivate methacholine blockade by atropine.
Architecture of Reconstructed Epidermis on Collagen Lattices Varies according to the Method Used: A Comparative Study
Authors: Lenoir M.C. , Bernard B.A.
Published: April 2009

Epidermis was obtained in vitro after air exposure of keratinocyte cultures grown on a dermal equivalent. Some cultures were established from enzymatically dissociated keratinocytes of either interfollicular epidermis or hair follicle outer root sheath. Others resulted from centrifugal outgrowth of epidermal sheet, out of skin biopsies or hair follicles, which were directly implanted into dermal equivalents. Whatever the system used, a multilayered epidermis was obtained with an overall architecture resembling that of human epidermis. However, depending on the tissue culture method used and the source of keratinocytes, significant differences were observed. The most striking finding was the difference in 67 kDa keratin expression: the only case where it was strictly suprabasal and homogeneously expressed in the cytoplasm of the cells, as in normal epidermis, was found in the epidermis obtained from hair follicle explants. With the other methods, the expression of this marker was delayed and patchy. These results are discussed in terms of possible intrinsic differences between interfollicular and follicular keratinocytes.
[3H]-13-cis-Retinoic Acid Covalently Binds to Thioredoxin Reductase in Human Keratinocytes
Authors: Schallreuter K.U. , Grebe T. , Pittelkow M.R. , Wood J.M.
Published: April 2009

13-cis-Retinoic acid is a stereospecific suicide inhibitor of thioredoxin reductase. [3H]-labeled 13-cis-retinoic acid has been used to covalently label thioredoxin reductase in human keratinocytes. The acid-soluble cytosol fraction of human keratinocytes contained three radioactive proteins labeled by the addition of high-specific-activity [3H]-13-cis-retinoic acid to cell cultures. One of these proteins was identified as cytosolic keratinocyte thioredoxin reductase by fast-protein liquid chromatography and SDS-gel radioautography. The inhibition of thioredoxin reductase by 13-cis-retinoic acid may explain the known cytostatic and teratogenic properties attributed to this retinoid.
Induction and Inhibition of NAD(P)H: Quinone Reductase in Murine and Human Skin
Authors: Merk H. , Jugert F. , Bonnekoh B. , Mahrle G.
Published: April 2009

The purpose of this study was to characterize the human cutaneous NAD(P)H: quinone reductase (NQR) activity by known inhibitors of different reductases and to compare it with the murine skin and liver NQR activity. This enzyme plays a major role in the defence of cells against oxygen stress because it inhibits the 1-electron reduction of quinones to semiquinones and their subsequent oxidation to quinones termed as quinone redox cycle. It belongs to the aromatic hydrocarbon-responsive (Ah) battery. This gene battery includes Cyplal (cytochrome P-450 IA1), Cypla2 (cytochrome P-450 IA2) and Nmo-1 [NAD(P)H: quinone reductase]. In the skin cytochrome P-450 IAl-dependent activity is about 1–5% compared to the corresponding activity in the liver, whereas NQR has the same activity in skin and liver. NQR was determined in the cytoplasm of murine skin, liver, and human keratinocytes using 2,6-dichlorophenolindophenol as the substrate. The Ah-receptor binding compounds, such as coal tar constituents, or 3-methylcholanthrene induce cytochrome P-450-dependent activities such as aryl hydrocarbon hydroxylase or 7-ethoxyresorufin-O-de-ethylase and NQR, whereas butyl hydroxytoluol, which does not bind to the Ah receptor, induces only NQR. For inhibition studies several known inhibitors of dihydrodiol dehydro-genase, aldo-keto and carbonyl reductase activities were used. There was a similar pattern of inhibition of the basal and induced activity in all tissues investigated. Pyrazole, progesterone and phenobarbital did not inhibit, whereas dicoumarol, rutin and indomethacin inhibited NQR activity in murine skin and liver as well as in human keratinocytes. This identical pattern of NQR inhibition in human keratinocytes, murine skin and liver suggests that the NQR in liver and skin, as well as in mouse and man may be similar and belong to the same gene family.
Percutaneous Penetration of Methyl Nicotinate at Three Anatomic Sites: Evidence for an Appendageal Contribution to Transport?
Authors: Tur Ethel , Maibach Howard I. , Guy Richard H.
Published: April 2009

Percutaneous absorption of the vasodilator methyl nicotinate (MN) was evaluated in human volunteers at three anatomic sites (forehead, forearm and palm) using the technique of laser Doppler flowmetry (LDF). The experiments were designed to test the hypothesis that the kinetics and extent of skin penetration are dependent upon the appendageal density at the site of application. The LDF technique measured the increase in skin blood flow elicited by topically applied MN once the chemical had penetrated to the microvasculature. Significant differences in the measured LDF responses at the three sites were found, and further analysis of the data suggested that MN penetration was greatest through forehead skin, least through the palm and intermediate across the skin of the forearm. A correlation therefore existed between apparent MN absorption and appendageal density.
Role of Cytoskeletons on Ca2+ Release from the Intracellular Ca Store of Rat Peritoneal Mast Cells
Authors: Tasaka Kenji , Mio Mitsunobu , Izushi Keiji
Published: April 2009

Cytochalasin D, colchicine or vinblastine effectively inhibited both histamine release and 45Ca uptake induced by compound 48/80 in rat mast cells. The inhibitory effects of cytochalasin D or colchicine on histamine release were exerted more remarkably when permeabilized mast cells were stimulated with either Ca2+ or inositol-1,4,5-trisphosphate (IP3). Since colchicine, vinblastine or cytochalasin D were not effective in inhibiting IP3 formation, it was assumed that microtubules or microfilaments may not participate in the initial stages of the membrane events leading to histamine release. By contrast, in Ca2+ release from the intracellular Ca store both colchicine and vinblastine (but not cytochalasin D) were effective in inhibiting Ca2+ mobilization, indicating that microtubules, rather than microfilaments, are intimately related to Ca2+ release from the endoplasmic reticulum (ER). By means of a fluorescence microscope, it was revealed that colchicine decreased the fluorescence intensity of FITC-labeled anti-tubulin antibody in the mast cells, while the amount of tubulin polymer in mast cells increased after exposure to compound 48/80. The findings indicate that colchicine simply suppressed polymerization of tubulin, while the rearrangement of microtubules so as to increase the polymerization took place after exposure to compound 48/80. Using an electron microscope in combination with potassium antimonate technique, Ca-antimonate dots were clearly observed in a cluster on the surface of the ER and a distinct connection between the ER and microtubules was also observed. It was concluded that microtubules play an important role in the processes leading to Ca2+ release from the intracellular Ca store and in subsequent histamine release.
Mast Cells and Their Mediators in Immediate and Delayed Immune Reactions
Authors: Möller A. , Grabbe J. , Czarnetzki B.M.
Published: April 2009

Tissue mast cells and the closely related blood basophils are distinguished by their special mediators and their high-affinity IgE membrane receptors. These properties have made the cells be viewed traditionally as effector cells of immediate-type hypersensitivity reactions. More recently, mast cells have been shown to develop from the myeloid series of the bone marrow under the influence of interleukins 3, 4, 6, 9, 10 and 11. Mast cell and basophil lines of murine and human origin have also been shown to express and release interleukins 1, 3, 4, 5, 6, 8, tumor necrosis factor-α, granulocyte-macrophage colony-stimulizing factor and interferon-γ. Certain cytokines are also able to induce mediator release from mast cells. Furthermore, mast cells have in the past been shown to be modestly phagocytic and to express major histocompatibility complex class II membrane markers after appropriate stimulation. These findings show that mast cells are intricately associated with immune reactions and suggest that they may not only sustain and modulate but possibly also initiate immune responses.
Inhibitory Effect of Loratadine and Clemastine on Histamine Release in Human Skin
Authors: Hägermark Östen , Wahlgren Carl-Fredrik , Giös Ingemar
Published: April 2009

The inhibitory effect of the two H1 antagonists clemastine and loratadine on histamine release in human skin was studied in 15 volunteers. The antihistamines and placebo were administered orally (clemastine 2 mg twice a day, loratadine 10 mg once a day) for 5 days according to a double-blind, crossover design. Clemastine caused a significant sedation in comparison with placebo, whereas there was no difference between loratadine and placebo in this respect. After 5 days’ medication, flare reaction was induced by intradermal injection of histamine and the histamine liberator compound 48/80. The antihistamine dosages were approximately equipotent and inhibited the flare response induced by histamine to about the same extent, whereas the flares induced by compound 48/80 were still more inhibited by both drugs. The results indicate that clemastine and loratadine not only inhibit histamine effects at H1 receptor level, but have additional suppressive effects, probably due to inhibition of mast cell degranulation. The simple, virtually noninvasive, in vivo technique described in this paper does not require chemical analysis of the released mediators and could be used to screen ‘mast cell stabilizing’ effects of various antihistamines.
Factors to Be Considered in the Evaluation of Bioavailability and Bioequivalence of Topical Formulations
Authors: Borsadia S. , Ghanem A.H. , Seta Y. , Higuchi W.I. , Flynn G.L. , Behl C.R. , Shah V.P.
Published: April 2009

In this paper, an attempt is made to find functional definitions of bioavailability and bioequivalence for topical products and to examine critical factors that influence topical bioavailability and bioequivalence. A physical model approach for quantifying the problem and increasing our understanding is presented here. The key assumptions are (1) that the target site is in the lower epidermis (basal layer) or in the dermis, and (2) that it is the thermodynamic activity (i.e., the free drug concentration, C*, of the active drug species) at the target site that is the true correlate of drug effectiveness. Studies initiated to implement the physical model approach involved first validating a ‘three-tiered’ model for finite dose drug uptake/transport in skin with experimentally determined input parameters (partition coefficient, K, and steady-state permeability coefficients, P, for the stratum corneum, viable epidermis, and dermis). Hydrocortisone was used as the model drug with hairless guinea pig skin as the model membrane. The physical model is used to show, via the C* concept, how formulation factors may influence bioavailability and bioequivalence. Finally, a method is presented for predicting the efficacy of topical formulations employing appropriate in vitro data and physical model calculations.
Strength and Viscoelastic Properties of Anisotropic Rat Skin after Treatment with Desmotropic Drugs
Authors: Vogel H.G.
Published: April 2009

Male Sprague-Dawley rats were treated 10 times either with 2 or 10 mg/kg s.c. prednisolone acetate or with 300 or 1,000 mg/kg p.o. D-penicillamine or with 100 or 300 mg/kg p.o. aminoacetonitrile bisulfate. Samples of dorsal skin were tested either longitudinally or perpendicularly to the body axis. Relaxation and hysteresis experiments were performed at different degrees of elongation. Finally, ultimate values were measured. In all groups, ultimate strain was much higher perpendicularly than longitudinally to the body axis. A dose-dependent increase of all parameters indicating strength or elasticity was found after prednisolone acetate treatment, whereas the indicators of viscosity showed a decrease. D-Peni-cillamine treatment decreased all parameters of strength and elasticity and increased viscosity and plasticity. Aminoacetonitrile bisulfate induced biphasic changes: after high-dose treatments strength and elasticity were increased and viscosity decreased. The results are discussed in view of changes of biochemical composition and cross-linking of collagen.
Biochemical Mechanisms Regulating Human Hair Growth
Authors: Sawaya Marty E.
Published: April 2009

The human hair follicle cycles in active growth and resting phases controlled by a complex network of biochemical processes, yet to be fully understood. It is well known that hair follicles on scalp respond to androgens by a shortening of the anagen growth phase causing hairs to regress to a finer, thinner texture. The target tissue androgens, testosterone, and dihy-drotestosterone can circulate systemically to skin or can be formed locally in hair follicles and sebaceous glands by specific enzymes in the steroid cascade. Kinetic constants have been evaluated for several enzymes which mediate dihydrotes-tosterone formation, including 5a-reductase, and the cyto-chrome P-450 aromatase enzyme in isolated human hair follicles and sebaceous glands from scalp of men and women with androgenetic alopecia. The levels of these enzymes differed between men and women, and from frontal versus occipital sites within the same patient, indicating that similar steroid mechanisms may be taking place in men and women, but the amount or level of enzymes vary, perhaps explaining why men have more severe patterns of hair loss than women. Knowing the differences between men and women with androgenetic alopecia could shape more effective treatment options in the future.
Cells in the Bulge of the Mouse Telogen Follicle Give Rise to the Lower Anagen Follicle
Authors: Wilson C.L. , Sun T.-T. , Lavker R.M.
Published: April 2009

The slow-cycling cells in the bulge of the outer root sheath may represent stem cells for the hair follicle. With each new anagen (growing) phase bulge cells would give rise to a population of transient-amplifying cells which differentiate into outer root sheath and matrix keratinocytes. The lowermost part of the telogen (resting) follicle is composed of bulge cells lying in close proximity to the dermal papilla. In the mouse the first hair follicle growth is characterized by rapid follicular neogen-esis, but the second and third growth cycles follow the normal follicular growth pattern. We have examined activity of cells in the bulge at the onset of anagen (growing phase) in the third hair cycle in Sencar mice, by treating animals at the end of the second telogen with colchicine to localize mitotic activity in the hair follicle. Mitoses were only seen in bulge cells during early anagen. This confirms that they proliferate transiently, solely at the onset of anagen and strongly supports the suggestion that bulge cells are the origin of the whole lower follicle in anagen.
Androgen Action in Cultured Dermal Papilla Cells from Human Hair Follicles
Authors: Randall Valerie A. , Thornton M. Julie , Hamada Kazuto , Messenger Andrew G.
Published: April 2009

Androgens are major regulators of human hair growth with paradoxically different effects on hair follicles depending on their body site. They stimulate terminal growth in many regions including the face, have no effect on eyelashes, but may cause inhibition and balding on the scalp in genetically disposed individuals. How this occurs is unknown. However, androgens may act on the hair follicle via the cells of the dermal papilla; these would then influence the other cells of the hair follicle by altering the production of regulatory substances such as growth factors and/or extracellular matrix components. Therefore, primary lines of dermal papilla cells have been established from androgen-sensitive hair follicles, such as beard, and control, relatively androgen-independent, non-balding scalp cells and their mechanism of androgen action has been compared. Isolated beard dermal papillae were larger than those from scalp follicles. Although dermal papilla cells did not respond to in vitro androgens by alterations in growth, androgen-dependent dermal papilla cells contained higher levels of specific, low capacity, high affinity androgen receptors than non-balding scalp cells. The ability of the cells to metabolise testosterone to 5α-dihydrotestosterone in culture also varied in parallel to that predicted from studies of hair growth in the 5α-reductase deficiency syndrome. These results support the hypothesis that androgens act via the dermal papilla. They also show that dermal papilla cells retain differences in gene expression in culture which appear to correspond with their androgenic response in vivo. Further studies of such cells should help elucidate why bald men can grow beards!
Cell Kinetics of Anagen Scalp Hairs under Physiological and Pathological Conditions
Authors: Kiesewetter F. , Schell H.
Published: April 2009

The cell kinetics of anagen scalp hair bulbs taken by punch biopsies from healthy male volunteers (n = 50) were determined at defined bulbar hair segments using microdissection and DNA flow cytometry. The highest proliferative activity (S phase) was measured within the lower most bulbar segment (14.0%) but decreased to the Auber’s segment (7.6%) and to the isthmus segment (5.9%). The results support histoautora-diographic data demonstrating most of the proliferative activity in the hair bulb below the Auber’s level [1]. Furthermore, cell kinetic data of dissected anagen hair bulbs segmented at Auber’s level from an androgen-sensitive scalp area were studied in male pattern baldness (n = 15, Hamilton IV) and hirsutism (n = 13). The results revealed a significant increase of S phase cells in male pattern baldness (8.9%) compared to healthy males (n = 10, 7.9%) as well as in hirsutism (10.2%) compared to healthy females (n = 10, 7.5%). In hirsutism the percentages of S phase cells ran parallel to the plasma levels of dehydroepiandrosterone sulfate whereas no correlation to testosterone could be proved. Similar, 6 hypothyroid and 6 hyperthyroid patients were studied. In hyperthyroidism an increase of S phase values (10.3%) was found, while it decreased in hypothyroidism (6.1%). A correlation between the height of S phase and plasma triiodothyronine level was noted. Our studies demonstrate that DNA flow cytometry is a suitable method for the evaluation of physiological or hormonal influences on cell cycle kinetics of human anagen hair bulbs in vivo.
In vivo Hydration Profile in Skin Layers by High-Resolution Magnetic Resonance Imaging
Authors: Querleux B. , Richard S. , Bittoun J. , Jolivet O. , Idy-Peretti I. , Bazin R. , Lévêque J.L.
Published: April 2009

In recent years magnetic resonance imaging has become a very efficient tool for in vivo quantification of water content and water behavior in living tissues. We have applied this technique to the study of the in vivo hydration profile in heel skin layers by quantification of the mobile water proton density versus depth. Effects of a bath, a moisturizer and repeated soaping are present. Hydration profiles by magnetic resonance imaging delineate two different structures in stratum corneum: an outer layer where hydration can be modified by external mechanisms and an inner layer where hydration is not altered. The main interest of this method lies in the fact that the physical signal is exactly located, as spatial encoding is the basis of in vivo imaging. This method differs from other noninvasive methods which acquire an averaged signal from a nondelimited volume of interest.
Percutaneous Absorption of Estradiol and Progesterone in Normal and Appendage-Free Skin of the Hairless Rat: Lack of Importance of Nutritional Blood Flow
Authors: Hueber F. , Besnard M. , Schaefer H. , Wepierre J.
Published: April 2009

Percutaneous absorption occurs after passive diffusion through the different layers of the skin and its appendages. Thereafter, a resorption process into the cutaneous microcirculation brings the compounds into the systemic circulation. The objective of this in vivo study in the hairless rat was to compare the percutaneous absorption of two steroids on normal and appendage-free (scar) skin and to show if differences in absorption result only from the lack of hair follicles and sebaceous glands and/or from a modification of local blood flow. Percutaneous absorption was evaluated with estradiol and progesterone after 30 min, 2 and 6 h. Except after 30 min, the reservoir function of the stratum corneum of scar skin was approximately twice as high as in normal skin. Eighty to ninety percent of the estradiol and progesterone found in the stratum corneum were located in its superficial layers. Inversely, whatever the application time was, the concentrations of both steroids in the epidermis and dermis were significantly higher in normal skin than in scar skin with maximal difference between about 40 and 400 µm, the area of sebaceous gland localization. Cutaneous blood flow in full-thickness skin, assessed by the thallium-201 method, was globally identical in normal and in scar skin. In scar skin, at the level of papillary dermis, a decrease in blood flow due to the thicker viable epidermis and the flat dermoepidermal junction has been shown without implying an accumulation of drug in the epidermis and superficial dermis. Under these conditions, our results clearly demonstrate that the nutritional blood flow does not interfere with the percutaneous absorption of estradiol and progesterone in normal and scar skin. Thus, they confirm the significant contribution of hair follicles and sebaceous glands to drug penetration into the skin and subsequently the systemic circulation.
Sonographic Quantification of the Type IV Reaction after Intradermal Application of Recall Antigens
Authors: Hoffmann Klaus , Feldmann Stefanie , Dirschka Thomas , Gammal Stefan el , Altmeyer Peter
Published: April 2009

20-MHz B-scan high-resolution sonography permits non-invasive, two-dimensional visualisation of micromorphological structures in vivo, and allows precise measurement of the depth and extent of inflammatory skin lesions. In 50 patients, the reactions following intradermal application of 8 recall antigens to the volar forearm were evaluated clinically and sonographically at various times (0, 24, 48, 72 h). In 30 patients, one of the inflammatory papules was excised after 48 h for complete histological work-up (serial sections) and subsequent comparison with the sonographic image. Infiltrates were characterised in the ultrasound scans by the almost regular occurrence of convexity of the skin surface, by a loosened structure (loss of echogenicity) of the corium and by protrusion of the corium into the subcutaneous fatty tissue. It was also possible to follow the dynamics of the type IV reaction with the measurement of echogenicity (densitometry). High-frequency ultrasound is an objective, exact and very sensitive tool for the measurement of type IV reactions after intradermal application of recall antigens and therefore superior to clinical evaluation. The B-scan was superior to the A-scan. However, for routine evaluation of tuberculin-like reactions, sonography is too time-consuming. Our results suggest that densitometry provides no additional or necessary information compared to sonometry.
Regulatory Effects of Antipsoriatic Agents on Interleukin-1 α Production by Human Keratinocytes Stimulated with Gamma Interferon in vitro
Authors: Maruyama Kohji , Zhang Jian-Zhong , Nihei Yoshimichi , Ono Ichiro , Kaneko Fumio
Published: April 2009

It is known that keratinocytes produce and secrete interleukin-1 (IL-1) de novo and that this process can be enhanced by various stimulators. IL-1 has been shown to be a potent proin-flammatory cytokine which mediates inflammation in various cutaneous disorders. It has also been demonstrated that Γ-interferon (IFN-Γ) which is released from infiltrated T cells can be detected in inflamed lesional sites. In order to understand the effects of IFN-Γ on IL-1 production by keratinocytes in such inflammatory lesions, normal human keratinocytes (NHKs) and human squamous cell carcinoma cell line (HSC-1) cells were cultivated with recombinant human IFN-Γ (rIFN-Γ) and IL·1 levels were measured by ELISA. The effects of antipsoriatic agents such as hydrocortisone (HC), cyclosporine A(CsA), 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and its analogue MC903 on IL-1 production by keratinocytes were also investigated. IL-1 release by both NHK and HSC-1 cells was accelerated by stimulation with rIFN-Γ dose-dependently, although IL-1Α was released only transiently by rlFN-Γ-stimu-lated NHKs in serum-free keratinocyte growth medium containing HC. Antihuman IFN-Γ antibody inhibited IL-lΑ release by HSC-1 cells stimulated with rIFN-Γ, suggesting that IL-1Α release from keratinocytes is upregulated by IFN-Γ. HC (5 µg/ml), 1,25(OH)2D3 (10-6M) and MC903 (10-6 M), but not CsA (5 µg/ml), inhibited IL-lΑ production by HSC-1 cells stimulated with 100 U/ml of rIFN-Γ. Since IL-l plays an important role in the initiation of cutaneous inflammation, its downregulation may prevent inflammation and thereby at least partly account for the clinical effectiveness of these agents in the treatment of psoriasis.
Effects of Selenium on UVA-lnduced Lipid Peroxidation in Cultured Human Skin Fibroblasts
Authors: Moysan A. , Morlière P. , Marquis I. , Richard A. , Dubertret L.
Published: April 2009

The effect of selenium on the lethal action of ultraviolet radiations and on the lipid peroxidation induced by exposures to ultraviolet A (320-400 nm; 360kJ·m-2) and ultraviolet B (290-320 nm; 2 kJ·m-2) have been measured in cultured human skin fibroblasts. The experiments have been performed with either pure selenium or a spring water containing selenium and other trace elements (zinc and strontium). For cells cultured in a standard medium containing 10% fetal calf serum, no effect of selenium or spring water addition to the culture medium was observed on the lethality or on the peroxi-dative process induced by ultraviolet A and B radiations. Concurrently, there was no detectable increase of the seleno-dependent glutathione peroxidase activity. For cells previously depleted in selenium by a culture in a medium containing only 2% serum, a protective effect of selenium can be detected. Depending on the fibroblast donor, we observed (1) a protective effect on lethality of dividing fibroblasts induced by ultraviolet A radiations, (2) a protective effect on lipid peroxidation induced by ultraviolet A radiations on dividing or quiescent fibroblasts and (3) an increase in glutathione peroxidase activity in fibroblasts.
Texture Analysis of the Surface of the Human Skin
Authors: Fiedler Martin , Meier Wolf-Dieter , Hoppe Udo
Published: April 2009

The roughness parameters known from surface engineering often used to describe the microtopography of the surface of the skin do not, by definition, take into account the two-dimensional relationships of the stratum corneum. An approximate description of these relationships can be obtained by scanning several radial profile sections. A more detailed analysis of the characteristic surface relief of the skin can also be based on the texture parameters used to characterize many natural structures. These types of parameters can be extracted from the gray level images of an impression of the surface of the skin – a replica – that has been magnified under a microscope, photographed with a CCD camera and subsequently subjected to image analysis by a digital computer.
Role of Retinoic Acid Receptor Gamma in the Rhino Mouse and Rabbit Irritation Models of Retinoid Activity
Authors: Reczek Peter R. , Ostrowski Jacek , Yu Kuo-Long , Chen Simon , Hammer Laura , Roalsvig Thor , Starrett Jr. John E. , Driscoll Joyce Phelan , Whiting Gary , Spinazze Patrick G. , Tramposch Kenneth M. , Mansuri Muzammil M.
Published: April 2009

The three retinoic acid receptors (RARΑ, RARΒ and RARΓ) are known to modulate the transcription of target genes through interaction of the individual receptors with their naturally occurring ligand, retinoic acid (RA). Since RA has multiple effects in vivo, considerable effort has recently been devoted to finding selective compounds to elucidate the functions of individual receptors and to relate these functions to specific in vivo effects. The racemic synthetic retinoid 6-[(5,5,8,8-tetramethyl- 5,6,7,8-tetrahydro-2 – naphthyl)hydroxy-methyl]-2-naphthalene carboxylic acid has recently been identified as an RARΓ-selective agonist. A synthetic method involving lipase-mediated transformation has been developed to prepare the individual enantiomers. Discrimination between the two enantiomers is seen in both transcriptional activity and binding to recombinant receptors with the (S)-enantiomer being the more active. Differences between the two compounds are also seen in the Rhino mouse utriculi reduction assay and the rabbit irritation model. In both animal models, the (S)-enantiomer consistently gave a greater response. Taken together, these results suggest that the activity and irritation seen with RA and related compounds is receptor mediated. Further, the strong selectivity of the compounds reported here for RARΓ suggests that this receptor plays an important role in these in vivo biological activities. The discrimination between these enantiomers may be useful in the design of novel retinoids with uniquely defined biological properties.
Cellular and Topical in vivo Inflammatory Murine Models in the Evaluation of Inhibitors of Phospholipase A2
Authors: Glaser Keith B. , Sung. Mei-Li A. , Hartman David A. , Lock Yeung W. , Bauer Jean , Walter Thomas , Carlson Ricard P.
Published: April 2009

Several novel inhibitors of human synovial fluid phospholipase A2 (HSF-PLA2) were evaluated in cellular models of inflammatory mediator release (murine macrophage and human neutrophil) and topical in vivo inflammatory skin models in mice to ascertain the scope of effects which might be observed for PLA2 inhibitors. Potent inhibition of HSF-PLA2 in vitro can be observed with compounds such as scalaradial and ellagic acid, which both have IC50 values of 0.02 µM (using autoclaved [3H]-arachi-donic-acid (AA)-labelled Escherichia coli membranes as substrate). Luffariellolide, a manoalide analog, and aristolochic acid are less potent (IC50 = 5 and 46 µM, respectively) in this assay. An interesting observation is that ellagic acid in cellular assays does not inhibit macrophage eicosanoid production and only 30% inhibition of PAF biosynthesis can be obtained at 50 µM in the human neutrophil. Possibly due to its irreversible mechanism of action, scalaradial retained its potent activity in both the macrophage (IC50 for PGE2 production = 0.05 µM) and neutrophil assays (IC50 for PAF biosynthesis = 1 µM). Aristolochic acid is active in these cellular assays (macrophage IC50 = 2.5 µM and neutrophil IC50 = 100 µM), but is consistently less active than either scalaradial or luffariellolide. The relative potencies of these compounds were determined in several murine in vivo inflammatory models such as oxazolone contact hypersensitivity, AA-induced ear edema and phorbol ester (PMA)-induced ear edema. In the mouse model of oxazolone contact hypersensitivity, these PLA2 inhibitors have little effect ( ≤ 30% inhibition at 400 µg/ear) with scalaradial and luffariellolide being less effective than either aristolochic or ellagic acid. PMA-induced ear edema was effectively inhibited by scalaradial, luffariellolide and aristolochic acid (ED50 = 70, 50 and 50 µg/ear, respectively) whereas ellagic acid was less effective (ED50 = 230 µg/ear). In AA-induced ear edema, these PLA2 inhibitors had minimal effects, as would be expected for compounds which inhibit PLA2. These results, especially those of ellagic acid, suggest that caution should be taken in the extrapolation of potency against a purified human extracellular type PLA2 to the scope of activities these compounds might have in the cellular and in vivo models. The consistency of scalaradial and luffariellolide may be inherent to their irreversible mechanism of action, which is a factor to be accounted for in the extrapolation of enzyme data to cellular and in vivo models.
Percutaneous Absorption, Excretion and Metabolism of All-trans-Retinoyl β-Glucuronide and of AII-trans-Retinoic Acid in the Rat
Authors: Barua Arun B. , Olson James A.
Published: April 2009

The purpose of these studies was to compare directly the percutaneous absorption, excretion and metabolism of all-trans-retinoyl Β-glucuronide (RAG), a nontoxic retinoid, with all-trans-retinoic acid (RA) in the rat. Previously, it was demonstrated that topical treatment of human acne with either RAG or RA in cream resulted in a significant reduction of lesions. Whereas 0.1 % RA showed adverse effects, concentrations of RAG up to 2.4% did not cause any adverse reactions. In the present studies, radiolabeled RAG or RA, dispersed in a water-based cream, was applied to the shaved dorsal skin of vitamin A-sufficient rats. Both RAG and RA were absorbed from the skin in a similar way. In both cases, radioactivity peaked in the plasma within 2-4 h and within the liver at 4-12 h. During a 7-day period, the overall excretion of radioactivity derived from RA and RAG in the feces and urine were similar, e.g. 17 and 12%, respectively. It is concluded that: (1)the transport, metabolism and excretion of topically applied radioactive RA and RAG are similar, although not identical, in the rat and (2) the toxic skin manifestations induced by RA but not by RAG cannot be attributed to major differences in their overall absorption, metabolism and excretion.
Simultaneous Absorption of Copper and Zinc through Human Skin in vitro
Authors: Pirot F. , Panisset F. , Agache P. , Humbert P.
Published: April 2009

Copper and zinc percutaneous absorptions were assessed in vitro using sliced human skin and both petrolatum and hydrophilic gels as vehicles. Applied quantities were largely in excess for the duration of the experiment (72 h). The absorption of sulphates and chlorides was compared. The cumulated amount recovered in receptor fluid was below 50 µg/cm2. The apparent permeability constant values kept in the range of 10-6 cm h-1, except for ZnCl2 in gel vehicle (2.9 10-5 cm h-1). With the exception of CuCl2 in gel vehicle, chlorides gave higher absorption rates than sulphates. This can be related to the higher octanol-water partition coefficient of chlorides. Storage within the epidermis was found to be equal to or greater than, and within the dermis equal to or lower than the 72-hour cumulative amount in receptor fluid. No difference was found in this respect between copper and zinc. This work confirms the poor absorption of electrolytes through normal human skin, whatever the vehicle used.