Probing Dynamic Behavior of Chemical Enhancers Passing In and Out of the Stratum Corneum and Modulation by Biodegradable Enhancer

2021 ◽  
Vol 22 (4) ◽  
Author(s):  
Lijuan Zeng ◽  
Guangqiang Yang ◽  
Jianping Liu ◽  
Danyi Quan ◽  
Wenting Song
Keyword(s):  
Stratum Corneum ◽  
Dynamic Behavior ◽  
Chemical Enhancers

scholarly journals Influence of Chemical Enhancers and Iontophoresis on the In Vitro Transdermal Permeation of Propranolol: Evaluation by Dermatopharmacokinetics

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 265 ◽  
Author(s):  
María Calatayud-Pascual ◽  
María Sebastian-Morelló ◽  
Cristina Balaguer-Fernández ◽  
M. Delgado-Charro ◽  
Alicia López-Castellano ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Stratum Corneum ◽  
Model Compound ◽  
Skin Permeation ◽  
Chemical Enhancer ◽  
Chemical Enhancers ◽  
Transdermal Permeation ◽  
Topical Bioavailability ◽  
Current Densities

The aims of this study were to assess, in vitro, the possibility of administering propranolol transdermally and to evaluate the usefulness of the dermatopharmacokinetic (DPK) method in assessing the transport of drugs through stratum corneum, using propranolol as a model compound. Four chemical enhancers (decenoic and oleic acid, laurocapram, and R-(+)-limonene) and iontophoresis at two current densities, 0.25 and 0.5 mA/cm2 were tested. R-(+)-limonene, and iontophoresis at 0.5 mA/cm2 were proven to be the most efficient in increasing propranolol transdermal flux, both doubled the original propranolol transdermal flux. Iontophoresis was demonstrated to be superior than the chemical enhancer because it allowed faster delivery of the drug. The DPK method was sufficiently sensitive to detect subtle vehicle-induced effects on the skin permeation of propranolol. The shorter duration of these experiments and their ability to provide mechanistic information about partition between vehicle and skin and diffusivity through skin place them as practical and potentially insightful approach to quantify and, ultimately, optimize topical bioavailability.

Changes in corneocyte element concentrations occur in skin inner stratum corneum

1990 ◽  
Vol 48 (2) ◽  
pp. 146-147
Author(s):  
R. R. Warner
Keyword(s):  
Stratum Corneum ◽  
Human Skin ◽  
Element Concentration ◽  
Skin Barrier ◽  
Barrier Properties ◽  
Brick Wall ◽  
Inorganic Elements ◽  
Dry Skin ◽  
Skin Biopsies ◽  
Intercellular Lipid

Keratinocytes undergo maturation during their transit through the viable layers of skin, and then abruptly transform into flattened, anuclear corneocytes that constitute the cellular component of the skin barrier, the stratum corneum (SC). The SC is generally considered to be homogeneous in its structure and barrier properties, and is often shown schematically as a featureless brick wall, the “bricks” being the corneocytes, the “mortar” being intercellular lipid. Previously we showed the outer SC was not homogeneous in its composition, but contained steep gradients of the physiological inorganic elements Na, K and Cl, likely originating from sweat salts. Here we show the innermost corneocytes in human skin are also heterogeneous in composition, undergoing systematic changes in intracellular element concentration during transit into the interior of the SC.Human skin biopsies were taken from the lower leg of individuals with both “good” and “dry” skin and plunge-frozen in a stirred, cooled isopentane/propane mixture.

Paracrystalline Aggregates of Psoriatic Keratin and Their Relation to Normal Keratin Structure

1985 ◽  
Vol 43 ◽  
pp. 680-681
Author(s):  
S. Trachtenberg ◽  
P.M. Steinert ◽  
B.L. Trus ◽  
A.C. Steven
Keyword(s):  
Cell Death ◽  
Stratum Corneum ◽  
Intermediate Filament ◽  
Skin Disease ◽  
Amorphous Matrix ◽  
Terminal Differentiation ◽  
Proteolytic Degradation ◽  
Horny Layer ◽  
Chronic Skin ◽  
Chronic Skin Disease

During terminal differentiation of vertebrate epidermis, certain specific keratin intermediate filament (KIF) proteins are produced. Keratinization of the epidermis involves cell death and disruption of the cytoplasm, leaving a network of KIF embedded in an amorphous matrix which forms the outer horny layer known as the stratum corneum. Eventually these cells are shed (desquamation). Normally, the processes of differentiation, keratinization, and desquamation are regulated in an orderly manner. In psoriasis, a chronic skin disease, a hyperkeratotic stratum corneum is produced, resulting in abnormal desquamation of unusually large scales. In this disease, the normal KIF proteins are diminished in amount or absent, and other proteins more typical of proliferative epidermal cells are present. There is also evidence of proteolytic degradation of the KIF.

Ball bearing turbocharger vibration management: application on high speed balancer

2020 ◽  
Vol 21 (6) ◽  
pp. 619
Author(s):  
Kostandin Gjika ◽  
Antoine Costeux ◽  
Gerry LaRue ◽  
John Wilson
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Ball Bearing ◽  
Squeeze Film ◽  
Design And Technology ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Bearing Loads ◽  
Stiffness And Damping

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

Rätselhafte Bläschen an Händen und Mundschleimhaut bei einem 15 Monate alten Mädchen: Intoxikation durch Dieselöl

2005 ◽  
Vol 5 (03) ◽  
pp. 141-143
Author(s):  
Andreas Merkenschlager ◽  
Matthias Bernhard
Keyword(s):  
Stratum Corneum

ZusammenfassungAkzidentelle Vergiftungen ereignen sich am häufigsten im Kleinkindesalter. Der weit verbreitete Gebrauch von aliphatischen Hydrokarbonen wie Dieselöl begünstigt Intoxikationen. Die Ingestion von Dieseltreibstoff birgt insbesondere die Gefahr einer Aspirationspneumonie. Akute Hauttoxizität ist hingegen selten.Ein 15 Monate altes Mädchen entwickelte nach vorausgegangenem Erbrechen und einer mehrere Stunden andauernden Lethargie innerhalb von 24 Stunden zahlreiche bläschenartige Hautläsionen, die teilweise ulzeriert waren, an den Fingern, der Handinnenfläche sowie perioral. Die Wangen- und Gaumensegelschleimhaut zeigten mehrere kleine Ulzera, die weißlich belegt und hämorrhagisch waren. Zunächst wurde eine Hand-Fuß-Mund-Krankheit vermutet. Durch ausführliche Anamnese konnte jedoch festgestellt werden, dass das Kind am Tag zuvor in einem Sandkasten gespielt hatte, der durch ein Leck in einem daneben stehenden Dieselöltank kontaminiert gewesen war. Eine pulmonale oder hepatische Beteiligung konnte nicht nachgewiesen werden. Die Läsionen heilten vollständig unter antiseptischen Verbänden innerhalb einer Woche ab.Man nimmt an, dass Dieselöl primär das Stratum corneum der Haut schädigt. Kinder sind aufgrund ihrer gegenüber Erwachsenen dünneren Hornhaut gefährdeter. In seltenen Fällen können sich Vesikel, Ulzera und Hämorrhagien entwickeln, die mit Infektionskrankheiten verwechselt werden können.Unstimmigkeiten bei klinischen Befunden sollten insbesondere bei Kleinkindern immer an mögliche Intoxikationen denken lassen.

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