[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.

Effects of different blood components on clot retraction analysed by measuring elasticity with a free oscillating rheometer

Free oscillation rheometry (FOR) using the ReoRox 4 instrument makes it possible, at bedside, to study the coagulation process in blood over time and gives information on clotting time and coagulum elastic properties. In order to find out how various factors influence the FOR analysis we studied the coagulation process and change of elasticity over time in non-anticoagulated and citrated blood samples, plasma samples with various platelet concentrations (0-200 x 109/l) and blood samples with various haematocrit (0-40%). Blood samples supplemented with fibrinogen were analysed to elucidate the importance of fibrinogen on elasticity. The importance of the GPIIb/IIIa receptor on platelets was investigated by comparing the elasticity development in blood samples in presence and absence of a GPIIb/IIIa receptor inhibitor, abciximab. Anticoagulation with citrate did not have major influence on the viscoelastic properties of the coagulum. Increasing number of platelets and increasing fibrinogen concentration resulted in higher elasticity while increasing haematocrit gave lower elasticity. Blood samples with GPIIb/IIIa receptor inhibitor had very low elasticity indicating the importance of functional GPIIb/IIIa receptors. In conclusion we consider FOR to be a useful method to study the elastic properties of the coagulum. Various factors such as the number of red blood cells and platelets as well as the fibrinogen concentration should be taken into consideration when evaluating the results. The ReoRox 4 instrument had excellent measuring range and unusually small artefactual effects on clot elasticity induced by the instrument in comparison with published results on other instruments.

The effects of perindopril on aortic elasticity and inflammatory markers in hypertensive patients

BACKGROUND

Inflammation plays an important role in hypertension and in atherosclerosis. Inflammatory changes induced even in prehypertensive subjects can lead to increased arterial stiffness. The effects of perindopril on both inflammatory and aortic elasticity markers were tested in hypertensive patients.

MATERIAL/METHODS

One hundred nine hypertensive patients not taking any antihypertensive therapy were included in the study. Aortic strain, aortic distensibility, aortic stiffness index, and inflammatory markers, including CRP, IL-1alpha IL-1beta, and TNF-alpha, were measured in all patients before and after twenty weeks of perindopril therapy.

RESULTS

While aortic strain and distensibility showed statistically significant increases with perindopril therapy, the aortic stiffness index and inflammatory markers were found to decrease.

CONCLUSIONS

Perindopril therapy resulted in an improvement in aortic elastic properties. There was also an attenuation of inflammatory status of the patients as reflected by lower inflammatory marker levels compared with pretreatment values.

A double injection ADSA-CSD methodology for lung surfactant inhibition and reversal studies

This paper presents a continuation of the development of a drop shape method for film studies, ADSA-CSD (Axisymmetric Drop Shape Analysis-Constrained Sessile Drop). ADSA-CSD has certain advantages over conventional methods. The development presented here allows complete exchange of the subphase of a spread or adsorbed film. This feature allows certain studies relevant to lung surfactant research that cannot be readily performed by other means. The key feature of the design is a second capillary into the bulk of the drop to facilitate addition or removal of a secondary liquid. The development will be illustrated through studies concerning lung surfactant inhibition. After forming a sessile drop of a basic lung surfactant preparation, the bulk phase can be removed and exchanged for one containing different inhibitors. Such studies mimic the leakage of plasma and blood proteins into the alveolar spaces altering the surface activity of lung surfactant in a phenomenon called surfactant inhibition. The resistance of the lung surfactant to specific inhibitors can be readily evaluated using the method. The new method is also useful for surfactant reversal studies, i.e. the ability to restore the normal surface activity of an inhibited lung surfactant film by using special additives. Results show a distinctive difference between the inhibition when an inhibitor is mixed with and when it is injected under a preformed surfactant film. None of the inhibitors studied (serum, albumin, fibrinogen, and cholesterol) were able to penetrate a preexisting film formed by the basic preparation (BLES and protasan), while all of them can alter the surface activity of such preparation when mixed with the preparation. Preliminary results show that reversal of serum inhibition can be easily achieved and evaluated using the modified methodology.

Impact of nitroglycerin and verapamil on coronary arterial distensibility as assessed by intravascular ultrasound

OBJECTIVES

To examine the effects of coronary artery vasodilators on coronary arterial distensibility using intravascular coronary ultrasound (IVUS).

BACKGROUND

There is limited information on the effect of coronary artery vasodilators on coronary arterial distensibility.

METHODS

We studied 20 patients using IVUS. Patients received 100 microg of nitroglycerin (10 patients) or 1 mg of verapamil (10 patients) intravenously. We measured coronary arterial elasticity, the distensibility index, compliance and stiffness index. There were no differences in patient characteristics, lesion characteristics or baseline coronary arterial distensibility between the two groups.

RESULTS

Systolic and diastolic blood pressure decreased in both groups (p < 0.05). Maximal coronary arterial cross-sectional luminal area (LA) during the cardiac cycle showed similar dilation in both groups. Nitroglycerin increased maximal LA by 5%, and verapamil increased it by 4% (p < 0.05; p < 0.0001, respectively). However, the degree of dilation of the minimal LA during the cardiac cycle showed a different pattern. Nitroglycerin dilated the minimal LA by 8%, while verapamil dilated the minimal LA by 2% (p < 0.001, p < 0.05, respectively). Consequently, the degree of expansion of LA during each cardiac cycle increased in the verapamil group and decreased in the nitroglycerin group. Thus, nitroglycerin decreased elasticity by 31% (p < 0.001), with no change in compliance, stiffness index or distensibility index. While, verapamil increased elasticity by 37%, the distensibility index by 48% and compliance by 53%, and decreased the stiffness index by 27% (all, p < 0.0001).

CONCLUSIONS

While both drugs acutely dilate the coronary arteries, nitroglycerin reduced local coronary arterial distensibility; however, verapamil increased local coronary arterial distensibility.

[Effects of CANELIM capsule drug-contained serum on viscoelasticity and adhesive mechanical properties of cholangiocarcinoma cells]

By way of gastrogavage, we administered CANELIM capsules to rat for prepering the drug-contained serums. And then the serums obtained were used to plant cholangiocarcinoma cells. Lastly, using the micropipette aspiration technique, we investigated the effects which the drug-contained serums of different doses have on the viscoelasticity and adhesive mechanical properties of cholangiocarcinoma cells. The results showed that cholangiocarcinoma cells presented a characteristic of high elastic coefficient and low viscous coefficient. After being treated by the high dose and middle dose drug-contained serums, the viscoelastical properties of cholangiocarcinoma cells K1, K2 and micro evidently decreased (P < 0.01). But the properties of low dose did not evidently change. The adhesive force between cholangiocarcinoma cells and CD44v6 protein significantly reduced with the increasing of the dose of CANELIM capsules (P < 0.01). It is suggested that CANELIM capsules would destroy the cytoskeleton of cholangiocarcinoma cells, restrain the adhesion molecule CD44v6 on membrane from expressing, reduce the adhesion probability between cholangiocarcinoma cells and vasal endothelial cells, and finally, prevent the metastasis of cholangiocarcinoma cells.

[Effect of tannic acid treatment on the physico-chemical properties of glutaraldehyde-fixed bovine jugular vein]

OBJECTIVE

To evaluate the effects of tannic acid (TA) treatment on the physico-chemical properties of glutaraldehyde (Glut)-fixed bovine jugular vein (BJV).

METHODS

Fresh BJVs were treated with Glut or Glut/TA, respectively. The shrinkage temperature, resistance to collagenase or elastase digestion, bio-mechanical properties, and molecular structure of these prepared BJVs were evaluated by Fourier transform infrared spectroscopy.

RESULTS

TA treatment resulted in higher shrinkage temperature (P < 0.01), higher resistance to collagenase or elastase digestion (P < 0.01), slightly increased tensile strength (P < 0.01), and elongation at break (P < 0.05) in Glut/TA BJV walls when compared with those of Glut group. Chemical bonds existed between TA and JBV tissue.

CONCLUSION

TA treatment can effectively improve the physicochemical properties of Glut-fixed BJVs.

The mechanical properties of individual, electrospun fibrinogen fibers

We used a combined atomic force microscopic (AFM)/fluorescence microscopic technique to study the mechanical properties of individual, electrospun fibrinogen fibers in aqueous buffer. Fibers (average diameter 208 nm) were suspended over 12 microm-wide grooves in a striated, transparent substrate. The AFM, situated above the sample, was used to laterally stretch the fibers and to measure the applied force. The fluorescence microscope, situated below the sample, was used to visualize the stretching process. The fibers could be stretched to 2.3 times their original length before breaking; the breaking stress was 22 x 10 (6)Pa. We collected incremental stress-strain curves to determine the viscoelastic behavior of these fibers. The total stretch modulus was 17.5 x 10 (6)Pa and the relaxed elastic modulus was 7.2 x 10 (6)Pa. When held at constant strain, electrospun fibrinogen fibers showed a fast and slow stress relaxation time of 3 and 55 s. Our fibers were spun from the typically used 90% 1,1,1,3,3,3-hexafluoro-2-propanol (90-HFP) electrospinning solution and re-suspended in aqueous buffer. Circular dichroism spectra indicate that alpha-helical content of fibrinogen is approximately 70% higher in 90-HFP than in aqueous solution. These data are needed to understand the mechanical behavior of electrospun fibrinogen structures. Our technique is also applicable to study other nanoscopic fibers.

Altering mucus rheology to "solidify" human mucus at the nanoscale

The ability of mucus to function as a protective barrier at mucosal surfaces rests on its viscous and elastic properties, which are not well understood at length scales relevant to pathogens and ultrafine environmental particles. Here we report that fresh, undiluted human cervicovaginal mucus (CVM) transitions from an impermeable elastic barrier to non-adhesive objects sized 1 microm and larger to a highly permeable viscoelastic liquid to non-adhesive objects smaller than 500 nm in diameter. Addition of a nonionic detergent, present in vaginal gels, lubricants and condoms, caused CVM to behave as an impermeable elastic barrier to 200 and 500 nm particles, suggesting that the dissociation of hydrophobically-bundled mucin fibers created a finer elastic mucin mesh. Surprisingly, the macroscopic viscoelasticity, which is critical to proper mucus function, was unchanged. These findings provide important insight into the nanoscale structural and barrier properties of mucus, and how the penetration of foreign particles across mucus might be inhibited.

[Clinical study of arterial rigidity. Part II. Remodeling of vessels in arterial hypertension and metabolic syndrome. possibilities of correction with drugs]

In the second part of the review we present data on vascular remodeling in arterial hypertension and metabolic syndrome with analysis of factors and mechanisms influencing pulse wave propagation velocity in these diseases. We also consider possibilities of correction of remodeling of vessels with contemporary antihypertensive drugs.

Ionotropic alginate beads for controlled intestinal protein delivery: Effect of chitosan and barium counter-ions on entrapment and release

Alginate beads containing the model protein haemoglobin (Hb) were prepared by coagulation with various counter-ions to improve the controlled release of the protein. The effect of Ba(2+) and Ca(2+) ions and of the polycationic polysaccharide chitosan was investigated. Coagulation with Ba(2+), Ca(2+) and/or chitosan showed differences in the swelling index of the beads, in the encapsulation efficiency of Hb entrapment and in the release of the entrapped protein. Chitosan in the coagulation fluid markedly enhanced the encapsulation efficiency of the Hb. Release studies were conducted in simulated gastric fluid (SGF pH approximately or equal to 1.2) and subsequently in simulated intestinal fluid (SIF ) at 37 degrees C. Beads were stable in the gastric fluid but released their protein upon transfer to intestinal fluid. The release coincides with the burst and disintegration of beads. Rate of protein release from the beads was affected by the Ba(2+) and chitosan concentration in coagulation fluid.

Transient binding and dissipation in cross-linked actin networks

In contrast with entangled actin solutions, transiently cross-linked actin networks can provide highly elastic properties while still allowing for local rearrangements in the microstructure-on biological relevant time scales. Here, we show that thermal unbinding of transient cross-links entails local stress relaxation and energy dissipation in an intermediate elasticity dominated frequency regime. We quantify the viscoelastic response of an isotropically cross-linked actin network by experimentally tuning the off rate of the transiently cross-linking molecules, their density, and the solvent viscosity. We reproduce the measured frequency response by a semiphenomenological model that is predicated on microscopic unbinding events.

Effect of topical application of raspberry ketone on dermal production of insulin-like growth factor-I in mice and on hair growth and skin elasticity in humans

Sensory neurons release calcitonin gene-related peptide (CGRP) on activation. We recently reported that topical application of capsaicin increases facial skin elasticity and promotes hair growth by increasing dermal insulin-like growth factor-I (IGF-I) production through activation of sensory neurons in mice and humans. Raspberry ketone (RK), a major aromatic compound contained in red raspberries (Rubus idaeus), has a structure similar to that of capsaicin. Thus, it is possible that RK activates sensory neurons, thereby increasing skin elasticity and promoting hair growth by increasing dermal IGF-I production. In the present study, we examined this possibility in mice and humans. RK, at concentrations higher than 1 microM, significantly increased CGRP release from dorsal root ganglion neurons (DRG) isolated from wild-type (WT) mice and this increase was completely reversed by capsazepine, an inhibitor of vanilloid receptor-1 activation. Topical application of 0.01% RK increased dermal IGF-I levels at 30 min after application in WT mice, but not in CGRP-knockout mice. Topical application of 0.01% RK increased immunohistochemical expression of IGF-I at dermal papillae in hair follicles and promoted hair re-growth in WT mice at 4 weeks after the application. When applied topically to the scalp and facial skin, 0.01% RK promoted hair growth in 50.0% of humans with alopecia (n=10) at 5 months after application and increased cheek skin elasticity at 2 weeks after application in 5 females (p<0.04). These observations strongly suggest that RK might increase dermal IGF-I production through sensory neuron activation, thereby promoting hair growth and increasing skin elasticity.

The effect of levothyroxine on arterial stiffness and lipid profile in patients with subclinical hypothyroidism

BACKGROUND

The influence of treatment for subclinical hypothyroidism (SCH) on cardiovascular morbidity and mortality, arterial stiffness, and lipid profile has not been elucidated yet. The aim of this study was to evaluate the effect of levothyroxine on arterial stiffness, lipid profile, and inflammation.

METHODS

The study included 30 patients with SCH. Patients were treated with levothyroxine and were assessed at baseline and at 1, 4, and 7 months. Blood samples were taken for lipid profile and highly sensitive C-reactive protein (hs-CRP). Arterial stiffness was evaluated by augmentation index (AIx). In conditions that cause arterial stiffness, the pulse wave traveling from the periphery to the heart reaches the heart during systole, resulting in augmentation of the central pressure. This increase, calculated as the AIx, is a good expression of central aortic pressure.

RESULTS

After accomplishing euthyroidism, the AIx decreased from 17.2 +/- 8.3 to 14.3 +/- 6.5 (p < 0.01) and AIx percentage decreased from 36.2 +/- 11.5 to 33.2 +/- 9.1 (p = 0.03). Systolic blood pressure (SBP) decreased from 134.7 +/- 20 to 127.6 +/- 13.7 mmHg (p < 0.01). In those patients whose AIx decreased, low-density lipoprotein (LDL) levels decreased by 0.4 +/- 0.96 mmol/L compared to the patients whose AIx did not decrease and LDL increased by 0.62 +/- 1.48 mmol/L (p = 0.057). Total cholesterol decreased by 0.72 +/- 1.64 mmol/L in the patients whose AIx decreased and increased by 1 +/- 2.53 mg/dL in the patients whose AIx did not improve (p = 0.06).

CONCLUSIONS

In patients with SCH, treatment with levothyroxine had a significant beneficial effect on arterial stiffness and SBP, and no effect on lipid profile or hs-CRP.

Effect of intensive statin therapy on arterial elasticity in patients with coronary artery disease

OBJECTIVE

Reduced arterial compliance is an independent predictor of cardiovascular mortality and is commonly encountered in patients with coronary artery disease. Statins may produce cholesterol-independent effects which can result at least in part from direct improvement of the arterial function. In this study, we sought to determine the effect of intensive statin therapy according to the Adult Treatment Panel III guidelines on arterial compliance in dyslipidaemic patients with angiographically-proven CAD selected for medical treatment.

METHODS

Patients (n = 33) received atorvastatin 40 mg/day for 6 months. Large arterial compliance and small arterial compliance were measured at baseline and after 6 months of atorvastatin treatment.

RESULTS

After treatment, the large artery elasticity index (LAEI) increased from 11.85 +/- 3.46 to 13.80 +/- 3.95 ml/mm Hg x 100 (P < 0.001) and the small artery elasticity index (SAEI) increased from 3.84 +/- 1.97 to 4.97 +/- 1.98 ml/mm Hg (P = 0.03). There was no correlation between the change in either LAEI or SAEI and other baseline variables or changes in lipid levels.

CONCLUSION

Our findings suggest that intensive statin therapy according to the Adult Treatment Panel III guidelines improves arterial elasticity in CAD patients selected for medical treatment. The beneficial vascular effect of atorvastatin on arterial elasticity was independent of lipid parameters.

Effect of long-term treatment with risedronate on arterial compliance in osteoporotic patients with cardiovascular risk factors

Accumulating evidence suggests that osteoporosis and coronary artery disease have epidemiologic similarities. Moreover, the anti-atherogenic effects of bisphosphonates have been observed in vitro and in animal models. The present study investigated the effect of risedronate on indices of arterial compliance, serum osteoprotegerin (OPG) level, inflammatory and metabolic parameters in osteoporotic women with cardiovascular risk factors. In an open label, prospective study 68 postmenopausal osteoporotic women were evaluated for the study. Patients received risedronate orally in a dose of 35 mg per week, daily supplements of calcium and cholecalciferol during 6month treatment period. Patients were evaluated for lipid profile, HbA1C, insulin, C-peptide, fibrinogen, hs-CRP and plasma osreoprotegerin. Arterial elasticity was evaluated using pulse wave contour analysis (HDI CR 2000, Eagan, Minnesota). Large artery elasticity index (LAEI) increased from 9.86+/-3.66 to 11.54+/-">+/-3.16 ml/mm HgX10 (p<0.0001) during treatment period. Small artery elasticity index (SAEI) increased from 2.64+/-1.10 to 3.28+/-1.16 ml/mm HgX100 (p<0.0001). Systemic vascular resistance (SVR) decreased from 1876.12+/-457.72 to 1646.12+/-260.17 dyn/s/cm(- 5) (p<0.013). Metabolic parameters did not change during the treatment period. Plasma osteoprotegerin was significantly, positively correlated to SVR at baseline (r=0.36, p=0.045). At the final visit, OPG was marginally inversely associated with LAE (r=- 0.312, p=0.09), and significantly, positively associated with total vascular impedance (r=0.43, p=0.015). In conclusion, prolonged treatment with risedronate improved arterial elasticity of small and large arteries, and decreased SVR. These beneficial vascular effects were not related to changes in cardiovascular risk factors and may be attributed to direct effects of risedronate on the vascular wall.

Short-term treatment with L-arginine prevents the smoking-induced impairment of endothelial function and vascular elastic properties in young individuals

BACKGROUND

L-arginine, the substrate for endothelial nitric oxide synthase, is essential for normal endothelial function. Aim of the present study was to investigate in healthy smokers the effect of a short-term daily L-arginine administration on vascular function.

METHODS

We studied the effect of a 3-day oral administration of L-arginine in 10 healthy smokers (24.3+/-0.73 years old) on 3 occasions (day , day 1 and day 3). The study was carried out on two separate arms, one with L-arginine (7 gr/d) and one with placebo according to a randomized, placebo-controlled, double-blind, cross-over design. Measurements were carried out before, immediately after (Sm0) and 20 min after (Sm20) cigarette smoking. Endothelial function was evaluated by flow-mediated dilatation (FMD) of the brachial artery. Carotid-femoral pulse wave velocity (PWV) was measured as an index of aortic stiffness and augmentation index (AIx) as a measure of arterial wave reflections.

RESULTS

Compared to placebo, L-arginine led to an increase of FMD (p<0.05 at day 2), indicating a favorable effect on endothelial function, which however lost significance at day 3. l-arginine induced a progressive decrease of PWV and AIx at both day 2 and day 3 (p<0.01 vs baseline for all). L-arginine blunted the acute smoking-induced increase of AIx at both day 1 (p<0.05) and day 3 (p<0.01), and there was a trend to protect the smoking-induced change of PWV at day 3 (p<0.1).

CONCLUSIONS

Short-term daily administration of L-arginine improves arterial performance in healthy smokers and abrogates the smoking-induced increase in arterial stiffness and wave reflections in these individuals.

Characterization of mineralized collagen-glycosaminoglycan scaffolds for bone regeneration

Mineralized collagen-glycosaminoglycan scaffolds designed for bone regeneration have been synthesized via triple co-precipitation in the absence of a titrant phase. Here, we characterize the microstructural and mechanical properties of these newly developed scaffolds with 50 and 75 wt.% mineral content. The 50 wt.% scaffold had an equiaxed pore structure with isotropic mechanical properties and a Ca-P-rich mineral phase comprised of brushite; the 75 wt.% scaffold had a bilayer structure with a pore size varying in the through-thickness direction and a mineral phase comprised of 67% brushite and 33 wt.% monetite. The compressive stress-strain response of the scaffolds was characteristic of low-density open-cell foams with distinct linear elastic, collapse plateau and densification regimes. The elastic modulus and strength of individual struts within the scaffolds were measured using an atomic force microscopy cantilevered beam-bending technique and compared with the composite response under indentation and unconfined compression. Cellular solids models, using the measured strut properties, overestimated the overall mechanical properties for the scaffolds; the discrepancy arises from defects such as disconnected pore walls within the scaffold. As the scaffold stiffness and strength decreased with increasing overall mineral content and were less than that of natural, mineralized collagen scaffolds, these microstructural/mechanical relations will be used to further improve scaffold design for bone regeneration applications.

Changes in the hyperelastic properties of endothelial cells induced by tumor necrosis factor-alpha

Mechanical properties of living cells can be determined using atomic force microscopy (AFM). In this study, a novel analysis was developed to determine the mechanical properties of adherent monolayers of pulmonary microvascular endothelial cells (ECs) using AFM and finite element modeling, which considers both the finite thickness of ECs and their nonlinear elastic properties, as well as the large strain induced by AFM. Comparison of this model with the more traditional Hertzian model, which assumes linear elastic behavior, small strains, and infinite cell thickness, suggests that the new analysis can predict the mechanical response of ECs during AFM indentation better than Hertz's model, especially when using force-displacement data obtained from large indentations (>100 nm). The shear moduli and distensibility of ECs were greater when using small indentations (<100 nm) compared to large indentations (>100 nm). Tumor necrosis factor-alpha induced changes in the mechanical properties of ECs, which included a decrease in the average shear moduli that occurred in all regions of the ECs and an increase in distensibility in the central regions when measured using small indentations. These changes can be modeled as changes in a chain network structure within the ECs.

Bone degeneration and recovery after early and late bisphosphonate treatment of ovariectomized wistar rats assessed by in vivo micro-computed tomography

Bisphosphonates are antiresorptive drugs commonly used to treat osteoporosis. It is not clear, however, what the influence of the time point of treatment is. Recently developed in vivo micro-computed tomographic (CT) scanners offer the possibility to study such effects on bone microstructure in rats. The aim of this study was to determine the influence of early and late zoledronic acid treatment on bone in ovariectomized rats, using in vivo micro-CT. Twenty-nine female Wistar rats were divided into the following groups: ovariectomy (OVX, n = 5), OVX and zoledronic acid (ZOL) at week 0 (n = 8), OVX and ZOL at week 8 (n = 7), and sham (n = 9). CT scans were made of the proximal tibia at weeks 0, 2, 4, 8, 12, and 16; and bone structural parameters were determined in the metaphysis. Two fluorescent labels were administered to calculate dynamic histomorphometric parameters. At week 16, all groups were significantly different from each other in bone volume fraction (BV/TV), connectivity density, and trabecular number (Tb.N), except for the early ZOL and control groups which were not significantly different for any structural parameter. After ZOL treatment at week 8, BV/TV, structure model index, Tb.N, and trabecular thickness significantly improved in the late ZOL group. The OVX and ZOL groups showed, respectively, higher and lower bone formation rates than the control group. Early ZOL treatment inhibited all bone microstructural changes seen after OVX. Late ZOL treatment significantly improved bone microstructure, although the structure did not recover to original levels. Early ZOL treatment resulted in a significantly better microstructure than late treatment. However, late treatment was still significantly better than no treatment.

High dose treatment with angiotensin II receptor blocker in patients with hypertension: Differential effect of tissue protection versus blood pressure lowering

Aggressive inhibition of renin-angiotensin-aldosterone system may provide the best cardiovascular protection. We examined the effect of different doses of angiotensin II receptor blocker, Candesartan, on arterial elasticity, inflammatory and metabolic parameters in hypertensive patients with multiple cardiovascular risk factors. 69 hypertensive patients were randomized into three groups: group 1 included patients treated with high doses of Candesartan (32 mg), group 2 included patients treated with conventional doses of Candesartan (16 mg), group 3 included patients that received antihypertensive treatment other that angiotensin II type-1 receptor blockers (ARBs) or angiotensin-converting enzyme inhibitors (ACEIs). Patients were evaluated for lipid profile, HbA1C, insulin, C-peptide, hs-CRP, aldosterone, renin and Homeostasis model assessment-insulin resistance (HOMA-IR). Arterial elasticity was evaluated using pulse wave contour analysis method (HDI CR 2000, Eagan, Minnesota). In patients treated with high doses of Candesartan: large artery elasticity index (LAEI) increased from 8.6+/-2.8 to 16.6+/-5.1 ml/mm Hg x 100 after 6 months of treatment (p<0.0001). Small artery elasticity index (SAEI) increased from 2.7+/-1.3 to 5.9+/-2.8 ml/mm Hg x 100 (p<0.0001). Systemic vascular resistance (SVR) decreased from 1881.5+/-527.5 to 1520.9+/-271.8 (p<0.0006). In patients treated with conventional doses of Candesartan: LAEI index increased from 11.0+/-3.5 to 14.4+/-3.2 ml/mm Hg x 100 (p<0.0001). SAEI increased during the study from 3.7+/-1.4 to 5.4+/-2.1 ml/mm Hg x 100 (p<0.0001). SVR decreased from 1699.8+/-327.6 to 1400.7+/-241 (p<0.0001). In the control group: neither LAE nor SAE improved during the treatment period. Although similar reduction in blood pressure was observed in all three groups, both LAE and SAE improved only in patients treated by ARBs. Treatment with high doses of Candesartan improves arterial stiffness to a greater extent than conventional doses of Candesartan, despite comparable changes in blood pressure.

Effects of treatment with parathyroid hormone 1-84 on quantity and biomechanical properties of thoracic vertebral trabecular bone in ovariectomized rhesus monkeys

Osteoporosis is characterized by impaired bone quality leading to increased susceptibility to fracture, particularly of the thoracic spine. However, the lumbar spine is studied most commonly. We investigated the effects of 16 months of treatment with full-length parathyroid hormone (PTH) 1-84 (5, 10, or 25 microg/kg) on bone mineral density (BMD) and on architecture and biomechanical properties of trabecular bone at the thoracic spine of ovariectomized (OVX) adult rhesus monkeys and compared the results with those from the lumbar spine. At baseline, 9 months after surgery, dual-energy X-ray absorptiometric BMD at T9-T12 was 7% lower in OVX than in sham animals. All PTH(1-84) doses increased BMD to sham levels within 7 months. Micro-computed tomography of T10 vertebrae showed that trabecular bone volume and connectivity were higher in PTH(1-84)-treated animals than in sham controls, primarily through a significantly greater trabecular number. Peripheral quantitative computed tomography of trabecular bone cores from T11 and T12 confirmed that PTH(1-84) increased BMD. Compression testing of the cores showed that PTH(1-84) treatment increased stiffness, modulus, yield load, and yield stress to levels significantly greater than in sham animals, with the largest effect in the 10 microg/kg group (35-54% greater than in OVX controls). Thus, PTH(1-84) treatment increased BMD and the biomechanical properties of trabecular bone at the thoracic spine of OVX rhesus monkeys. The 10 microg/kg dose produced the greatest effect on trabecular strength, possibly because the highest dose stimulated bone remodeling excessively. Importantly, the changes observed were similar to those in lumbar vertebrae, thereby validating extrapolation of results from the lumbar to the thoracic spine.

Arterial elasticity and plasma levels of adiponectin and leptin in type 2 diabetic patients treated with thiazolidinediones

BACKGROUND

Thiazolidinediones (TZDs) improve peripheral insulin sensitivity, but the effect on arterial stiffness is less clear. The aim of the present study was to assess the differential effect of pioglitazone or rosiglitazone on arterial stiffness and plasma levels of adiponectin and leptin in patients with type 2 diabetes mellitus.

METHODS

Thirty-five type 2 diabetic subjects were randomly assigned to receive pioglitazone (30 mg/day; n = 14), rosiglitazone (4 mg/day; n = 11), or placebo (medical nutrition therapy; n = 10) for 12 weeks. Changes in plasma glucose, glycosylated hemoglobin, insulin resistance (HOMA-IR), total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, adiponectin, and leptin were evaluated at baseline and after 12 weeks. In parallel, large arterial compliance (C1) and small arterial compliance (C2) were measured at baseline and at the end of treatment period.

RESULTS

At 12 weeks, the rosiglitazone (P = 0.026) and pioglitazone (P = 0.004) groups had a significant increase from baseline in adiponectin that was not seen in the medical nutrition therapy group. No significant changes in plasma leptin and in C1 and C2 elasticity indexes were observed over the entire study period in any of the treatment groups.

CONCLUSIONS

In this study of patients with type 2 diabetes, treatment with TZDs was associated with a significant improvement in adiponectin levels, although no significant effects were seen on leptin levels and arterial elasticity.