Calendula extract: effects on mechanical parameters of human skin

The aim of this study was to evaluate the effects of newly formulated topical cream of Calendula officinalis extract on the mechanical parameters of the skin by using the cutometer. The Cutometer 580 MPA is a device that is designed to measure the mechanical properties of the skin in response to the application of negative pressure. This non-invasive method can be useful for objective and quantitative investigation of age related changes in skin, skin elasticity, skin fatigue, skin hydration, and evaluation of the effects of cosmetic and antiaging topical products. Two creams (base and formulation) were prepared for the study. Both the creams were applied to the cheeks of 21 healthy human volunteers for a period of eight weeks. Every individual was asked to come on week 1, 2, 3, 4, 5, 6, 7, and 8 and measurements were taken by using Cutometer MPA 580 every week. Different mechanical parameters of the skin measured by the cutometer were; R0, R1, R2, R5, R6, R7, and R8. These were then evaluated statistically to measure the effects produced by these creams. Using ANOVA, and t-test it was found that R0, and R6 were significant (p <0.05) whereas R1, R2, R5, R7, R8 were insignificant (p > 0.05). The instrumental measurements produced by formulation reflected significant improvements in hydration and firmness of skin.

Effect of Chinese herbal medicine for calming Gan (肝) and suppressing hyperactive yang on arterial elasticity function and circadian rhythm of blood pressure in patients with essential hypertension

OBJECTIVE

To observe the effect of Chinese herbal medicine for calming Gan (肝) and suppressing hyperactive yang (平肝潜阳, CGSHY) on arterial elasticity function and the circadian rhythm of blood pressure in patients with essential hypertension (EH).

METHODS

Adopting a parallel, randomized design, sixty-four patients with EH of stages I and II were randomly divided into two groups according to a random number table, with 32 in each group. The patients in the treatment group were treated with CGSHY and those in the control group were treated with Enalapril. All patients were given 24-h ambulatory blood pressure monitoring (ABPM) before and after a 12-week treatment. Trough/peak (T/P) ratios of systolic and diastolic blood pressure (SBP & DBP) of each group were calculated. The circadian rhythm of their blood pressure was observed at the same time. The changes in elasticity of the carotid artery in the patients, including stiffness parameter (β), pressure-strain elastic modulus (Ep), arterial compliance (AC), augmentation index (AI), and pulse wave velocity (PVWβ) were determined by the echo-tracking technique before and after a 12-week treatment. In the meantime, their levels of nitric oxide (NO) and endothelin-1 (ET-1) were measured respectively.

RESULTS

After treatment, all parameters in the 24-h ABPM and the elasticity of the carotid artery (β, Ep, AC and PVWβ) were markedly improved, the level of NO was increased, and ET-1 was decreased in both groups as compared with values before treatment (P<0.05 or P<0.01). Further, the improvements in the ratio of T/P of SBP & DBP and in the level of NO and ET-1 in the treatment group were more significant than those in the control group (P<0.05). There were no significant differences in all parameters in the ABPM monitoring and the elasticity of the carotid artery, the recovery of blood pressure circadian rhythm, and the therapeutic effect of antihypertension in EH patients between the two groups (P>0.05).

CONCLUSIONS

Chinese herbal medicine for CGSHY may lower the blood pressure smoothly and recover the circadian rhythm of blood pressure in EH patients. They may also improve the carotid elasticity of EH patients similar to that of Enalapril. The mechanism of action of Chinese herbs on EH might be related to the regulation of vascular endothelium function.

Nitrite supplementation reverses vascular endothelial dysfunction and large elastic artery stiffness with aging

We tested the hypothesis that short-term nitrite therapy reverses vascular endothelial dysfunction and large elastic artery stiffening with aging, and reduces arterial oxidative stress and inflammation. Nitrite concentrations were lower (P < 0.05) in arteries, heart, and plasma of old (26-28 month) male C57BL6 control mice, and 3 weeks of sodium nitrite (50 mg L(-1) in drinking water) restored nitrite levels to or above young (4-6 month) controls. Isolated carotid arteries of old control mice had lower acetylcholine (ACh)-induced endothelium-dependent dilation (EDD) (71.7 ± 6.1% vs. 93.0 ± 2.0%) mediated by reduced nitric oxide (NO) bioavailability (P < 0.05 vs. young), and sodium nitrite restored EDD (95.5 ± 1.6%) by increasing NO bioavailability. 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL), a superoxide dismutase (SOD) mimetic, apocynin, a nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) inhibitor, and sepiapterin (exogenous tetrahydrobiopterin) each restored EDD to ACh in old control, but had no effect in old nitrite-supplemented mice. Old control mice had increased aortic pulse wave velocity (478 ± 16 vs. 332 ± 12 AU, P < 0.05 vs. young), which nitrite supplementation lowered (384 ± 27 AU). Nitrotyrosine, superoxide production, and expression of NADPH oxidase were ∼100-300% greater and SOD activity was ∼50% lower in old control mice (all P < 0.05 vs. young), but were ameliorated by sodium nitrite treatment. Inflammatory cytokines were markedly increased in old control mice (P < 0.05), but reduced to levels of young controls with nitrite supplementation. Short-term nitrite therapy reverses age-associated vascular endothelial dysfunction, large elastic artery stiffness, oxidative stress, and inflammation. Sodium nitrite may be a novel therapy for treating arterial aging in humans.

Coupling of gelatin to inner surfaces of pore walls in spongy alginate-based scaffolds facilitates the adhesion, growth and differentiation of human bone marrow mesenchymal stromal cells

We have developed a novel wide-pore scaffold for cell 3D culturing, based on the technology of freeze-drying of Ca-alginate and gelatin. Two different preparation methodologies were compared: (i) freeze-drying of Na-alginate + gelatin mixed solution followed by the incubation of dried polymer in saturated ethanolic solution of CaCl₂; (ii) freeze-drying of the Na-alginate solution followed by the chemical "activation" of polysaccharide core with divinylsulfone with subsequent gelatin covalent attachment to the inner surfaces of pore walls. The scaffolds produced using the first approach did not provide adhesion and proliferation of human bone marrow mesenchymal stromal cells (MSCs). Conversely, the second approach allowed to obtain scaffolds with a high adherence ability for the cells. When cultured within the latter type of scaffold, MSCs proliferated and were able to differentiate into adipogenic, osteogenic and chondrogenic cell lineages, in response to specific induction stimuli. The results indicate that Ca-alginate wide-pore scaffolds with covalently attached gelatin could be useful for stem cell-based bone, cartilage and adipose tissue engineering.

Is vascular stiffness a target for therapy?

BACKGROUND

Early cardiovascular disease starts in the endothelium leading to functional changes in the vasculature. These changes can be depicted by assessment of arterial stiffness or elasticity. There are several techniques to assess arterial stiffness. Increased arterial stiffness or decreased arterial elasticity has been associated with cardiovascular risk factors. There is now evidence that small artery elasticity is a strong predictor for arterial hypertension. Moreover arterial elasticity provides extra prognostic information beyond arterial blood pressure measurement. Arterial stiffness attenuation may reflect the true reduction of arterial wall damage.

RESULTS

ACE-inhibitors, angiotensin II receptor blockers, aldosterone antagonists and calcium antagonists have favorable effects in improving arterial elasticity, while beta-blockers have an inverse effect. Diuretics have not been evaluated. Lipid lowering therapy, some antidiabetic therapy have shown to reduce arterial stiffness. Inflammatory and infectious diseases have been associated with vascular inflammation and consequently increase in arterial stiffness. The effect of anti-inflammatory agents and antiretroviral therapy on arterial stiffness is under investigation.

CONCLUSIONS

Measurement of arterial stiffness will not only be helpful in the detection of early vascular disease but also as a tool in the selection and follow-up monitoring of therapeutic strategies aimed at preventing or delaying progression of vascular disease.

[Regulation of the functional and mechanical properties of platelet and red blood cells by nitric oxide donors]

The effect of NO donors (sodium nitroprusside, S-nitrosoglutathione, dinitrosyl-iron complexes) on the functional and mechanical properties of human platelets and red blood cells has been investigated. It has been established by atomic force microscopy that NO donor-induced platelet disaggregation is accompanied by changes in the elastic properties of cells. It has been shown that, in the presence of NO donors, the detergent-induced hemolysis of red blood cells is delayed, and the elasticity modulus of these cells decreases. The results obtained indicate that NO donors regulate the structural and functional properties of platelets and red blood cells.

Biophysical properties of normal and diseased renal glomeruli

The mechanical properties of tissues and cells including renal glomeruli are important determinants of their differentiated state, function, and responses to injury but are not well characterized or understood. Understanding glomerular mechanics is important for understanding renal diseases attributable to abnormal expression or assembly of structural proteins and abnormal hemodynamics. We use atomic force microscopy (AFM) and a new technique, capillary micromechanics, to measure the elastic properties of rat glomeruli. The Young's modulus of glomeruli was 2,500 Pa, and it was reduced to 1,100 Pa by cytochalasin and latunculin, and to 1,400 Pa by blebbistatin. Cytochalasin or latrunculin reduced the F/G actin ratios of glomeruli but did not disrupt their architecture. To assess glomerular biomechanics in disease, we measured the Young's moduli of glomeruli from two mouse models of primary glomerular disease, Col4a3(-/-) mice (Alport model) and Tg26(HIV/nl) mice (HIV-associated nephropathy model), at stages where glomerular injury was minimal by histopathology. Col4a3(-/-) mice express abnormal glomerular basement membrane proteins, and Tg26(HIV/nl) mouse podocytes have multiple abnormalities in morphology, adhesion, and cytoskeletal structure. In both models, the Young's modulus of the glomeruli was reduced by 30%. We find that glomeruli have specific and quantifiable biomechanical properties that are dependent on the state of the actin cytoskeleton and nonmuscle myosins. These properties may be altered early in disease and represent an important early component of disease. This increased deformability of glomeruli could directly contribute to disease by permitting increased distension with hemodynamic force or represent a mechanically inhospitable environment for glomerular cells.

Characterization of glycidyl methacrylate - crosslinked hyaluronan hydrogel scaffolds incorporating elastogenic hyaluronan oligomers

Prior studies on two-dimensional cell cultures suggest that hyaluronic acid (HA) stimulates cell-mediated regeneration of extracellular matrix structures, specifically those containing elastin, though such biologic effects are dependent on HA fragment size. Towards being able to regenerate three-dimensional (3-D) elastic tissue constructs, the present paper studies photo-crosslinked hydrogels containing glycidyl methacrylate (GM)-derivatized bio-inert high molecular weight (HMW) HA (1 × 10(6)Da) and a bioactive HA oligomer mixture (HA-o: MW ∼0.75 kDa). The mechanical (rheology, degradation) and physical (apparent crosslinking density, swelling ratio) properties of the gels varied as a function of incorporated HA oligomer content; however, overall, the mechanics of these hydrogels were too weak for vascular applications as stand-alone materials. Upon in vivo subcutaneous implantation, only a few inflammatory cells were evident around GM-HA gels, however their number increased as HA-o content within the gels increased, and the collagen I distribution was uniform. Smooth muscle cells (SMC) were encapsulated into GM hydrogels, and calcein acetoxymethyl detection revealed that the cells were able to endure twofold the level of UV exposure used to crosslink the gels. After 21 days of culture, SMC elastin production, measured by immunofluorescence quantification, showed HA-o to increase cellular deposition of elastic matrix twofold relative to HA-o-free GM-HA gels. These results demonstrate that cell response to HA/HA-o is not altered by their methacrylation and photo-crosslinking into a hydrogel, and that HA-o incorporation into cell-encapsulating hydrogel scaffolds can be useful for enhancing their production of elastic matrix structures in a 3-D space, important for regenerating elastic tissues.

Lattice strains and load partitioning in bovine trabecular bone

Microdamage and failure mechanisms have been well characterized in bovine trabecular bone. However, little is known about how elastic strains develop in the apatite crystals of the trabecular struts and their relationship with different deformation mechanisms. In this study, wide-angle high-energy synchrotron X-ray diffraction has been used to determine bulk elastic strains under in situ compression. Dehydrated bone is compared to hydrated bone in terms of their response to load. During compression, load is initially borne by trabeculae aligned parallel to loading direction with non-parallel trabeculae deforming by bending. Ineffective load partitioning is noted in dehydrated bone whereas hydrated bone behaves like a plastically yielding foam.

Alpha-ketoglutarate stabilizes redox homeostasis and improves arterial elasticity in aged mice

The objective of this study was to evaluate the effect of α-ketoglutarate on redox state parameters and arterial elasticity in elderly mice. Mice in the control group were fed with standard diet, while the experimental animals received the diet supplemented either with calcium (Ca-AKG) or sodium salt of α-ketoglutarate (Na-AKG). The experimental animals were divided into 4 groups with 10 individuals in each: control I (12 months old), control II (2 months old), experimental group I fed with Ca-AKG (12 months old) and experimental group II fed with Na-AKG (12 months old). Mice treated with Ca-AKG as well as the control II animals demonstrated significantly higher level of total antioxidant status (TAS), comparing to the control I animals and those treated with Ca-AKG. Thiobarbituric acid reactive substances (TBARS) level in blood plasma was found significantly lower in young and Ca-AKG treated mice. TBARS liver concentration was significantly different in each examined group. The study also demonstrates the decrease in TBARS level in Ca-AKG treated animals. Treatment with Na-AKG significantly increased glutathione peroxidase activity and decreased the activity of superoxide dismutase. The presented results suggest that Ca-AKG protects the organism against the free radicals related elderly processes. The study presents also the effect of Ca-AKG treatment on arterial elastic characteristics in elderly mice. The beneficial effect of Ca-AKG on ageing organisms was confirmed via redox state stabilization and blood vessel elasticity improvement.

Chemical and antimicrobial treatments change the viscoelastic properties of bacterial biofilms

Changes in the viscoelastic material properties of bacterial biofilms resulting from chemical and antimicrobial treatments were measured by rheometry. Colony biofilms of Staphylococcus epidermidis or a mucoid Pseudomonas aeruginosa were subjected to a classical creep test performed using a parallel plate rheometer. Data were fit to the 4-parameter Burger model to quantify the material properties. Biofilms were exposed to the chloride salts of several common mono-, di-, and tri- valent cations, and to urea, industrial biocides, and antibiotics. Many of these treatments resulted in statistically significant alterations in the material properties of the biofilm. Multivalent cations stiffened the P. aeruginosa biofilm, while ciprofloxacin and glutaraldehyde weakened it. Urea, rifampin, and a quaternary ammonium biocide weakened the S. epidermidis biofilm. In general, there was no correspondence between the responses of the two different types of biofilms to a particular treatment. These results underscore the distinction between the killing power of an antimicrobial agent and its ability to alter biofilm mechanical properties and thereby influence biofilm removal. Understanding biofilm rheology and how it is affected by chemical treatment could lead to improvements in biofilm control.

Mechanical evaluation of the resistance and elastance of post-burn scars after topical treatment with tretinoin

OBJECTIVE

After burn injuries, scarred skin lacks elasticity, especially in hypertrophic scars. Topical treatment with tretinoin can improve the appearance and quality of the skin (i.e., texture, distensibility, color, and hydration). The objective of this prospective study was to examine the effects of treatment with 0.05% tretinoin for one year on the biomechanical behavior and histological changes undergone by facial skin with post-burn scarring.

SETTING

Tertiary, Institutional.

METHOD

Fifteen female patients who had suffered partial thickness burns with more than two years of evolution were selected. Skin biopsies were obtained initially and after one year of treatment. The resistance and elastance of these skin biopsies were measured using a mechanical oscillation analysis system. The density of collagen fibers, elastic fibers, and versican were determined using immunohistochemical analysis.

RESULTS

Tretinoin treatment significantly lowered skin resistance and elastance, which is a result that indicates higher distensibility of the skin. However, tretinoin treatment did not significantly affect the density of collagen fibers, elastic fibers, or versican.

CONCLUSION

Topical tretinoin treatment alters the mechanical behavior of post-burn scarred skin by improving its distensibility and thus leads to improved quality of life for patients.

Comparative study of the topical application of Aloe vera gel, therapeutic ultrasound and phonophoresis on the tissue repair in collagenase-induced rat tendinitis

The aim of our study was to compare topical use of Aloe vera gel, pulsed mode ultrasound (US) and Aloe vera phonophoresis on rat paw with collagenase-induced tendinitis. Edema size, tensile tendon strength, tendon elasticity, number of inflammatory cells and tissue histology were studied at 7 and 14 days after tendinitis induction. Pulse mode US parameters were: 1 MHz frequency, 100 Hz repetition rate, 10% duty cycle, and 0.5 W/cm(2) intensity, applied for 2 min each session. A 0.5 mL of Aloe vera gel at 2% concentration was applied for 2 min per session, topically and by phonophoresis. Topical application of Aloe vera gel did not show any statistically significant improvement in the inflammatory process, whereas phonophoresis enhanced the gel action reducing edema and number of inflammatory cells, promoting the rearrangement of collagen fibers and promoting also the recovery of the tensile strength and elasticity of the inflamed tendon to recover their normal pre-injury status. Results seem to indicate that Aloe vera phonophoresis is a promising technique for tendinitis treatment, without the adverse effect provoked by systemic anti-inflammatory drugs.

Vascular differentiation of bone marrow stem cells is directed by a tunable three-dimensional matrix

Microenvironmental cues are critical in regulating cell behavior and fate. The roles that matrix mechanical signals play in regulating cell behavior have recently been elucidated. An artificial matrix that can maintain the appropriate characteristics for transplanted stem cells is therefore needed to achieve a desired cell phenotype. The objective of this study was to develop a three-dimensional (3-D) matrix with tunable physical and mechanical properties and investigate their effects on mesenchymal stem cell (MSC) differentiation towards vascular cell types. In this study we developed an extracellular microenvironment by modifying fibrinogen with various polyethylene glycol (PEG) derivatives. We hypothesized that adjusting the type of PEG derivative to modify the resultant physical and mechanical characteristics of fibrin would allow us to create a tunable system for use in culture or in vivo in conjunction with a regenerative medicine strategy. Human MSC (hMSC) were entrapped into PEGylated fibrin matrices at a density of 50,000 cells ml(-1). Cell phenotypes were confirmed by immunofluorescent staining as well as the use of oligonucleotide arrays. Vascular phenotypes were correlated with measured mechanical properties and fiber diameters of the PEGylated fibrin matrices. Blocking studies were performed to identify mechanistic factors controlling MSC differentiation through selected blocking of matrix degradation or cell contraction. Cell-matrix interactions were also examined in vivo. Our results demonstrate that transdifferentiation of MSC towards an endothelial cell phenotype is profoundly affected by the 3-D matrix microenvironment. Our work provides a predictive road map for the creation of fibrin-based matrices that support robust endothelial cell gene expression and tubulogenesis.

Actin filament length tunes elasticity of flexibly cross-linked actin networks

Networks of the cytoskeletal biopolymer actin cross-linked by the compliant protein filamin form soft gels that stiffen dramatically under shear stress. We demonstrate that the elasticity of these networks shows a strong dependence on the mean length of the actin polymers, unlike networks with small, rigid cross-links. This behavior is in agreement with a model of rigid filaments connected by multiple flexible linkers.

Effects of L-alanine and inosine germinants on the elasticity of Bacillus anthracis spores

The surface of dormant Bacillus anthracis spores consists of a multilayer of protein coats and a thick peptidoglycan layer that allow the cells to resist chemical and environmental insults. During germination, the spore coat is degraded, making the spore susceptible to chemical inactivation by antisporal agents as well as to mechanical inactivation by high-pressure or mechanical abrasion processes. While chemical changes during germination, especially the release of the germination marker, dipicolinic acid (DPA), have been extensively studied, there is as yet no investigation of the corresponding changes in the mechanical properties of the spore. In this work, we use atomic force microscopy (AFM) to characterize the mechanical properties of the surface of Bacillus anthracis spores during germination. The Hertz model of continuum mechanics of contact was used to evaluate the Young's moduli of the spores before and after germination by applying the model to load-indentation curves. The highest modulus was observed for dormant spores, with average elasticity values of 197 +/- 81 MPa. The elasticity decreased significantly after incubation of the spores with the germinants L-alanine or inosine (47.5 +/- 41.7 and 35.4 +/- 15.8 MPa, respectively). Exposure of B. anthracis spores to a mixture of both germinants resulted in a synergistic effect with even lower elasticity, with a Young's modulus of 23.5 +/- 14.8 MPa. The elasticity of the vegetative B. anthracis cells was nearly 15 times lower than that of the dormant spores (12.4 +/- 6.3 MPa vs 197.0 +/- 80.5 MPa, respectively). Indeed from a mechanical strength point of view, the germinated spores were closer to the vegetative cells than to the dormant spores. Further, the decrease in the elasticity of the cells was accompanied by increasing AFM tip indentation depths on the cell surfaces. Indentation depths of up to 246.2 nm were observed for vegetative B. anthracis compared to 20.5 nm for the dormant spores. These results provide quantitative information on how the mechanical properties of the cell wall change during germination, which may explain how spores become susceptible to inactivation processes based on mechanical forces during germination and outgrowth. The study of spore elasticity may be a valuable tool in the design of improved antisporal treatments.

Viscoelastic response of photo-cross-linked poly(N-isopropylacrylamide) coatings by QCM-D

The viscoelastic behavior of surface-tethered poly(N-isopropylacrylamide), or poly(NIPAAm), networks in contact with aqueous solutions was characterized by the quartz crystal microbalance with dissipation (QCM-D). To avoid ambiguities in the data analysis, four integer multiples of the dry thickness (h = k x 36 nm, where k = 1, 2, 3, 4) were analyzed at the third through ninth overtones of the QCM-D signal. At the third overtone, the networks resembled rigid films and the viscoelastic behavior could not be ascertained. With increasing overtones, however, the films showed deviation from the rigid film limit, allowing for analysis of the viscoelastic parameters. As the network collapsed over the temperature range of 15-40 degrees C, the shear modulus of the network increased by a factor of 24 (from 5 to 120 MPa); the shear viscosity, on the other hand, increased only by a factor of 2 (from 40 to 80 cP). The high values of the shear modulus suggest the QCM-D probes a regime where the polymer mesh does not adequately relax, and the high values of the shear viscosity suggest significant polymer-polymer coil overlap above and below the demixing temperature. Finally, the influence of NaCl on the viscoelastic response was measured. Interestingly, NaCl affects the shear modulus of the networks but not the dynamics.

Passive and active microrheology for cross-linked F-actin networks in vitro

Actin filament (F-actin) is one of the dominant structural constituents in the cytoskeleton. Orchestrated by various actin-binding proteins (ABPs), F-actin is assembled into higher-order structures such as bundles and networks that provide mechanical support for the cell and play important roles in numerous cellular processes. Although mechanical properties of F-actin networks have been extensively studied, the underlying mechanisms for network elasticity are not fully understood, in part because different measurements probe different length and force scales. Here, we developed both passive and active microrheology techniques using optical tweezers to estimate the mechanical properties of F-actin networks at a length scale comparable to cells. For the passive approach we tracked the motion of a thermally fluctuating colloidal sphere to estimate the frequency-dependent complex shear modulus of the network. In the active approach, we used an optical trap to oscillate an embedded microsphere and monitored the response in order to obtain network viscoelasticity over a physiologically relevant force range. While both active and passive measurements exhibit similar results at low strain, the F-actin network subject to high strain exhibits non-linear behavior which is analogous to the strain-hardening observed in macroscale measurements. Using confocal and total internal reflection fluorescent microscopy, we also characterize the microstructure of reconstituted F-actin networks in terms of filament length, mesh size and degree of bundling. Finally, we propose a model of network connectivity by investigating the effect of filament length on the mechanical properties and structure.

Flexible and elastic porous poly(trimethylene carbonate) structures for use in vascular tissue engineering

Biocompatible and elastic porous tubular structures based on poly(1,3-trimethylene carbonate), PTMC, were developed as scaffolds for tissue engineering of small-diameter blood vessels. High-molecular-weight PTMC (M(n) = 4.37 x 10(5)) was cross-linked by gamma-irradiation in an inert nitrogen atmosphere. The resulting networks (50-70% gel content) were elastic and creep resistant. The PTMC materials were highly biocompatible as determined by cell adhesion and proliferation studies using various relevant cell types (human umbilical vein endothelial cells (HUVECs), smooth muscle cells (SMCs) and mesenchymal stem cells (MSCs)). Dimensionally stable tubular scaffolds with an interconnected pore network were prepared by particulate leaching. Different cross-linked porous PTMC specimens with average pore sizes ranging between 55 and 116 microm, and porosities ranging from 59% to 83% were prepared. These scaffolds were highly compliant and flexible, with high elongations at break. Furthermore, their resistance to creep was excellent and under cyclic loading conditions (20 deformation cycles to 30% elongation) no permanent deformation occurred. Seeding of SMCs into the wall of the tubular structures was done by carefully perfusing cell suspensions with syringes from the lumen through the wall. The cells were then cultured for 7 days. Upon proliferation of the SMCs, the formed blood vessel constructs had excellent mechanical properties. Their radial tensile strengths had increased from 0.23 to 0.78 MPa, which is close to those of natural blood vessels.

[Effects of SERMs on bone health. SERM actions other than on the bones. With special reference to the actions of SERM on the skin and vascular elasticity]

Raloxifene, a selective estrogen receptor modulator (SERM), was developed with the aim of preventing and treating postmenopausal osteoporosis. Raloxifene is frequently compared to estrogen preparations, and it is considered that besides its actions on the bone, raloxifene also has actions on the skin and vascular elasticity in a way similar to estrogen preparations. Some reports have recently shown improvement of the skin elasticity following administration of raloxifene or transdermal and oral administration of estrogen preparations. Arterial elasticity has been reported to be improved by transdermal administration of an estrogen preparation, but not by raloxifene. However, there have been very few reports on these actions of raloxifene, and many points remain unclear concerning the effects of this drug class in the present clinical situation. Future studies are expected to clarify the actions of SERM other than on the bones, and also reveal the action mechanisms of drugs belonging to this class.

Microtubule elasticity: connecting all-atom simulations with continuum mechanics

The mechanical properties of microtubules have been extensively studied using a wide range of biophysical techniques, seeking to understand the mechanics of these cylindrical polymers. Here we develop a method for connecting all-atom molecular dynamics simulations with continuum mechanics and show how this can be applied to understand microtubule mechanics. Our coarse-graining technique applied to the microscopic simulation system yields consistent predictions for the Young's modulus and persistence length of microtubules, while clearly demonstrating how binding of the drug Taxol decreases the stiffness of microtubules. The techniques we develop should be widely applicable to other macromolecular systems.

[Side effects of caffeine]

Caffeine is one of the most commonly ingested alkaloids worldwide. It is present in coffee, tea, soft and energy drinks, chocolate, etc. Currently published data has been stressed that the metyloxantine consumption increases the risk of coronary heart disease, arterial hypertension, arterial stiffness, and an elevation of cholesterol and homocysteine plasma concentration. The acute high consumption may also modulate insulin sensitivity and glucose blood level. However, the long-term consumption reduces the incidence of the type 2 diabetes mellitus. When administered in high doses the substance may cause various side effects, related to abnormal stimulation of the central nervous system, decrease tonus of the lower esophageal sphincter, as well as increase risk of miscarriage and intrauterine growth retardation. The final manifestation of side reactions is dependent on the genotype, especially polymorphisms of genes associated with caffeine metabolism, i.e., cytochrome P450-CYP1A2 and catechol-O-methyltransferase (COMT).

Detailed scaling analysis of low-force polyelectrolyte elasticity

Single-molecule force-extension data are typically compared to ideal models of polymer behavior that ignore the effects of self-avoidance. Here, we demonstrate a link between single-molecule data and the scaling pictures of a real polymer. We measure a low-force elasticity regime where the extension L of chemically denatured single-stranded DNA grows as a power law with force f : L approximately f;{gamma} , with gamma approximately 0.60-0.69 . This compares favorably with the "tensile-blob" model of a self-avoiding polymer, which predicts gamma=2/3 . We show that the transition out of the low-force regime is highly salt dependent, and use the tensile-blob model to relate this effect to the salt dependence of the polymer's Kuhn length and excluded-volume parameter. We find that, contrary to the well-known Odijk-Skolnick-Fixman theory, the Kuhn length of single-stranded DNA is linearly proportional to the Debye length of the solution. Finally, we show that the low-force elasticity becomes linear (gamma=1) at approximately 3 M salt, and interpret this as a Theta point of the polymer. At this point, the force-extension data is best described by the wormlike chain model, from which we estimate the bare (nonelectrostatic) persistence length of the polymer to be approximately 0.6 nm .

A stabilized 0.1% retinol facial moisturizer improves the appearance of photodamaged skin in an eight-week, double-blind, vehicle-controlled study

Retinol is a cosmetic ingredient that is structurally similar to all-trans-retinoic acid, which has been shown to be effective in the treatment of photodamage. Since skin keratinocytes are reported to metabolize retinol to retinoic acid, investigators have hypothesized that retinol may also be helpful in improving skin photodamage. In this eight-week, double-blind, split-face, randomized clinical study, a stabilized 0.1% retinol-containing moisturizer was tested (36 subjects) against the vehicle (28 subjects) in women with moderate facial photodamage. Each product was applied once daily to the designated half side of the face. Subjects were evaluated at baseline and after four and eight weeks of treatment using a 0-9 scale for photoaging parameters. The results showed that, after eight weeks, the retinol moisturizer was significantly more efficacious than the vehicle in improving lines and wrinkles, pigmentation, elasticity, firmness and overall photodamage. Many of these differences were significant at week 4, with a progressive improvement to week 8. This study demonstrates that a formulation containing stabilized retinol is safe and effective to ameliorate the appearance of photoaged skin.