Polycrystalline Transparent Al-Doped ZnO Thin Films for Photosensitivity and Optoelectronic Applications.

Thin nanocrystalline transparent Al-doped ZnO (1-10 at.% Al) films were synthesized by solid-phase pyrolysis at 700 °C. Synthesized Al-doped ZnO films were investigated by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM). All obtained materials were crystallized into the wurtzite structure, which was confirmed by XRD. The material crystallinity decreases with the introduction of aluminum. SEM and TEM showed that the films are continuous and have a uniform distribution of nanoparticles with an average size of 15-20 nm. TEM confirmed the production of Al-doped ZnO films. The transmittance of Al-doped ZnO films in the range of 400-1000 nm is more than 94%. The introduction of 1% Al into ZnO leads to a narrowing of the band gap compared to ZnO to a minimum value of 3.26 eV and a sharp decrease in the response time to the radiation exposure with a wavelength of 400 nm. An increase in aluminum concentration leads to a slight increase in the band gap, which is associated with the Burstein-Moss effect. The minimum response time (8 s) was shown for film containing 10% Al, which is explained by the shortest average lifetime of charge carriers (4 s).

Nanocomposite Co3O4-ZnO Thin Films for Photoconductivity Sensors.

Thin nanocomposite films based on zinc oxide (ZnO) added with cobalt oxide (Co3O4) were synthesized by solid-phase pyrolysis. According to XRD, the films consist of a ZnO wurtzite phase and a cubic structure of Co3O4 spinel. The crystallite sizes in the films increased from 18 nm to 24 nm with growing annealing temperature and Co3O4 concentration. Optical and X-ray photoelectron spectroscopy data revealed that enhancing the Co3O4 concentration leads to a change in the optical absorption spectrum and the appearance of allowed transitions in the material. Electrophysical measurements showed that Co3O4-ZnO films have a resistivity up to 3 × 104 Ohm∙cm and a semiconductor conductivity close to intrinsic. With advancing the Co3O4 concentration, the mobility of the charge carriers was found to increase by almost four times. The photosensors based on the 10Co-90Zn film exhibited a maximum normalized photoresponse when exposed to radiation with wavelengths of 400 nm and 660 nm. It was found that the same film has a minimum response time of ca. 26.2 ms upon exposure to radiation of 660 nm wavelength. The photosensors based on the 3Co-97Zn film have a minimum response time of ca. 58.3 ms versus the radiation of 400 nm wavelength. Thus, the Co3O4 content was found to be an effective impurity to tune the photosensitivity of radiation sensors based on Co3O4-ZnO films in the wavelength range of 400-660 nm.

Recycling of Epoxy/Fiberglass Composite Using Supercritical Ethanol with (2,3,5-Triphenyltetrazolium)2[CuCl4] Complex.

The widespread use of polymer composite materials (PCM) leads to an increase in non-recyclable waste. This paper discusses the feasibility of recycling fiberglass with an epoxy matrix by solvolysis in ethanol under supercritical conditions. The solvolysis process completes successfully within four hours in an environment of a pure solvent containing 10% water at a temperature of 280 °C when the solvent passes into the supercritical state. The treatment time increases up to 10 h at a process temperature of 250 °C. When using a coordination compound of copper(II) chloride with organic chloride salt having 2,3,5-triphenyltetrazolium as the counterion, having the composition of (2,3,5-triphenyltetrazolium)2[CuCl4], the treatment time is reduced. The addition of the complex of 5% by weight makes it possible to completely remove the epoxy matrix at a temperature of 250 °C for two hours. The products separated from the solvolysis liquid were studied by infrared spectroscopy. The resulting fibers were examined by thermogravimetric analysis and scanning electron microscopy. The residual strength of the recovered fibers is 98%. Thus, the resulting fibers can be reused in the composite industry. Including both for the production of decorative products and for the production of structural products made of polymer composite materials.

High Gas Sensitivity to Nitrogen Dioxide of Nanocomposite ZnO-SnO2 Films Activated by a Surface Electric Field.

Gas sensors based on the multi-sensor platform MSP 632, with thin nanocomposite films based on tin dioxide with a low content of zinc oxide (0.5-5 mol.%), were synthesized using a solid-phase low-temperature pyrolysis technique. The resulting gas-sensitive ZnO-SnO2 films were comprehensively studied by atomic force microscopy, Kelvin probe force microscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy, energy dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy. The obtained films are up to 200 nm thick and consist of ZnO-SnO2 nanocomposites, with ZnO and SnO2 crystallite sizes of 4-30 nm. Measurements of ZnO-SnO2 films containing 0.5 mol.% ZnO showed the existence of large values of surface potential, up to 1800 mV, leading to the formation of a strong surface electric field with a strength of up to 2 × 107 V/cm. The presence of a strong surface electric field leads to the best gas-sensitive properties: the sensor's responsivity is between two and nine times higher than that of sensors based on ZnO-SnO2 films of other compositions. A study of characteristics sensitive to NO2 (0.1-50 ppm) showed that gas sensors based on the ZnO-SnO2 film demonstrated a high sensitivity to NO2 with a concentration of 0.1 ppm at an operating temperature of 200 °C.

Frontiers of protected areas versus forest exploitation: Assessing habitat network functionality in 16 case study regions globally.

Exploitation of natural forests forms expanding frontiers. Simultaneously, protected area frontiers aim at maintaining functional habitat networks. To assess net effects of these frontiers, we examined 16 case study areas on five continents. We (1) mapped protected area instruments, (2) assessed their effectiveness, (3) mapped policy implementation tools, and (4) effects on protected areas originating from their surroundings. Results are given as follows: (1) conservation instruments covered 3-77%, (2) effectiveness of habitat networks depended on representativeness, habitat quality, functional connectivity, resource extraction in protected areas, time for landscape restoration, "paper parks", "fortress conservation", and data access, (3) regulatory policy instruments dominated over economic and informational, (4) negative matrix effects dominated over positive ones (protective forests, buffer zones, inaccessibility), which were restricted to former USSR and Costa Rica. Despite evidence-based knowledge about conservation targets, the importance of spatial segregation of conservation and use, and traditional knowledge, the trajectories for biodiversity conservation were generally negative.

Brain Genomics Superstruct Project initial data release with structural, functional, and behavioral measures.

The goal of the Brain Genomics Superstruct Project (GSP) is to enable large-scale exploration of the links between brain function, behavior, and ultimately genetic variation. To provide the broader scientific community data to probe these associations, a repository of structural and functional magnetic resonance imaging (MRI) scans linked to genetic information was constructed from a sample of healthy individuals. The initial release, detailed in the present manuscript, encompasses quality screened cross-sectional data from 1,570 participants ages 18 to 35 years who were scanned with MRI and completed demographic and health questionnaires. Personality and cognitive measures were obtained on a subset of participants. Each dataset contains a T1-weighted structural MRI scan and either one (n=1,570) or two (n=1,139) resting state functional MRI scans. Test-retest reliability datasets are included from 69 participants scanned within six months of their initial visit. For the majority of participants self-report behavioral and cognitive measures are included (n=926 and n=892 respectively). Analyses of data quality, structure, function, personality, and cognition are presented to demonstrate the dataset's utility.

Bottlenose dolphins modify behavior to reduce metabolic effect of tag attachment.

Attaching bio-telemetry or -logging devices ('tags') to marine animals for research and monitoring adds drag to streamlined bodies, thus affecting posture, swimming gaits and energy balance. These costs have never been measured in free-swimming cetaceans. To examine the effect of drag from a tag on metabolic rate, cost of transport and swimming behavior, four captive male dolphins (Tursiops truncatus) were trained to swim a set course, either non-tagged (n=7) or fitted with a tag (DTAG2; n=12), and surface exclusively in a flow-through respirometer in which oxygen consumption VO2 and carbon dioxide production (VO2; ml kg(-1) min(-1)) rates were measured and respiratory exchange ratio (VO2/resting VO2) was calculated. Tags did not significantly affect individual mass-specific oxygen consumption, physical activity ratios (exercise /resting ), total or net cost of transport (COT; J m(-1) kg(-1)) or locomotor costs during swimming or two-minute recovery phases. However, individuals swam significantly slower when tagged (by ~11%; mean ± s.d., 3.31±0.35 m s(-1)) than when non-tagged (3.73±0.41 m s(-1)). A combined theoretical and computational fluid dynamics model estimating drag forces and power exertion during swimming suggests that drag loading and energy consumption are reduced at lower swimming speeds. Bottlenose dolphins in the specific swimming task in this experiment slowed to the point where the tag yielded no increases in drag or power, while showing no difference in metabolic parameters when instrumented with a DTAG2. These results, and our observations, suggest that animals modify their behavior to maintain metabolic output and energy expenditure when faced with tag-induced drag.

Reversible and irreversible differentiation of cardiac fibroblasts.

AIMS: Differentiation of cardiac fibroblasts (Fbs) into myofibroblasts (MyoFbs) is responsible for connective tissue build-up in myocardial remodelling. We examined MyoFb differentiation and reversibility. METHODS AND RESULTS: Adult rat cardiac Fbs were cultured on a plastic substratum providing mechanical stress, with conditions to obtain different levels of Fb differentiation. Fb spontaneously differentiated to proliferating MyoFb (p-MyoFb) with stress fibre formation decorated with alpha-smooth muscle actin (α-SMA). Transforming growth factor-ß1 (TGF-ß1) promoted differentiation into α-SMA-positive MyoFb showing near the absence of proliferation, i.e. non-p-MyoFb. SD-208, a TGF-ß-receptor-I (TGF-ß-RI) kinase blocker, inhibited p-MyoFb differentiation as shown by stress fibre absence, low α-SMA expression, and high proliferation levels. Fb seeded in collagen matrices induced no contraction, whereas p-MyoFb and non-p-MyoFb induced 2.5- and four-fold contraction. Fb produced little collagen but high levels of interleukin-10. Non-p-MyoFb had high collagen production and high monocyte chemoattractant protein-1 and tissue inhibitor of metalloproteinases-1 levels. Transcriptome analysis indicated differential activation of gene networks related to differentiation of MyoFb (e.g. paxilin and PAK) and reduced proliferation of non-p-MyoFb (e.g. cyclins and cell cycle regulation). Dedifferentiation of p-MyoFb with stress fibre de-polymerization, but not of non-p-MyoFb, was induced by SD-208 despite maintained stress. Stress fibre de-polymerization could also be induced by mechanical strain release in p-MyoFb and non-p-MyoFb (2-day cultures in unrestrained 3-D collagen matrices). Only p-MyoFb showed true dedifferentiation after long-term 3-D cultures. CONCLUSIONS: Fb, p-MyoFb, and non-p-MyoFb have a distinct gene expression, ultrastructural, and functional profile. Both reduction in mechanical strain and TGF-ß-RI kinase inhibition can reverse p-MyoFb differentiation but not non-p-MyoFb.

Inhibition of superoxide dismutase induces collagen production in cardiac fibroblasts.

BACKGROUND: The aim of this study was to determine whether inhibition of superoxide dismutase (SOD) with diethyldithiocarbamic acid (DETC) could affect the collagen production, the mRNA and protein expression of collagen types I and III, and fibronectin in control and angiotensin II (ANG II)-treated cardiac fibroblasts. Its effect was compared with the SOD mimetics tempol and EUK-8 and with polyethyleneglycol (PEG)-SOD. METHODS: Cardiac fibroblasts were cultured to confluence, incubated in serum-free Dulbecco's modified Eagle's medium for 24 h, preincubated with(out) the tested inhibitors for 1 h and further incubated with(out) ANG II (1 micromol/l) for 24 h. RESULTS: DETC dose-dependently inhibited the activity of CuZn-SOD in cardiac fibroblasts. Superoxide anion production was increased by DETC and decreased by tempol in control and ANG II-treated fibroblasts. DETC also reduced the intracellular generation of reactive oxygen species (ROS) (such as H2O2, hydroxyl radicals, hydroperoxides) in control and ANG II-treated fibroblasts, whereas tempol reduced the ROS production only in ANG II-treated fibroblasts. ANG II and DETC stimulated the collagen production and the collagen I and fibronectin content in fibroblasts. The SOD mimetics tempol and EUK-8 as well as PEG-SOD reduced the collagen production. ANG II and DETC stimulated the tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2 levels, whereas tempol decreased the TIMP-2 content in control and ANG II-treated fibroblasts. Matrix metalloproteinase (MMP)-1 level was reduced by ANG II and DETC and increased by tempol. CONCLUSION: These data suggest a vital role of SOD and the formed ROS in the accumulation of collagen in cardiac fibroblasts.

TGF-beta1-induced cardiac myofibroblasts are nonproliferating functional cells carrying DNA damages.

TGF-beta1 induces differentiation and total inhibition of cardiac MyoFb cell division and DNA synthesis. These effects of TGF-beta1 are irreversible. Inhibition of MyoFb proliferation is accompanied with the expression of Smad1, Mad1, p15Ink4B and total inhibition of telomerase activity. Surprisingly, TGF-beta1-activated MyoFbs are growth-arrested not only at G1-phase but also at S-phase of the cell cycle. Staining with TUNEL indicates that these cells carry DNA damages. However, the absolute majority of MyoFbs are non-apoptotic cells as established with two apoptosis-specific methods, flow cytometry and caspase-dependent cleavage of cytokeratin 18. Expression in MyoFbs of proliferative cell nuclear antigen even in the absence of serum confirms that these MyoFbs perform repair of DNA damages. These results suggest that TGF-beta1-activated MyoFbs can be growth-arrested by two checkpoints, the G1/S checkpoint, which prevents cells from entering S-phase and the intra-S checkpoint, which is activated by encountering DNA damage during the S phase or by unrepaired damage that escapes the G1/S checkpoint. Despite carrying of the DNA damages TGF-beta1-activated MyoFbs are highly functional cells producing lysyl oxidase and contracting the collagen matrix.

Optical detection of the Casimir force between macroscopic objects.

We report the optical detection of mechanical deformation of a macroscopic object induced by the Casimir force. An adaptive holographic interferometer based on a photorefractive BaTiO3:Co crystal was used to measure periodical nonlinear deformations of a thin pellicle caused by an oscillating Casimir force. A reasonable agreement between the experimental and calculated values of the first and second harmonics of the Casimir force oscillations has been obtained.

Angiotensin II-stimulated collagen production in cardiac fibroblasts is mediated by reactive oxygen species.

OBJECTIVE: The aim of the present study was to determine whether inhibition of reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] oxidase and of various superoxide generating systems could affect the collagen production, the mRNA and protein expression of collagen types I and III in control and angiotensin II-treated cardiac fibroblasts. METHODS: Cardiac fibroblasts from passage 2 from normal male adult rats were cultured to confluency and incubated in serum-free Dulbecco's modified Eagle's medium for 24 h. The cells were then preincubated with(out) the tested inhibitors for 1 h and then further incubated with(out) angiotensin II (1 micromol/l) for 24 h. Collagen production was measured spectrophotometrically with picrosirius red as dye and with [3H]proline incorporation; collagen type I and III content by enzyme-linked immunosorbent assay and collagen type I and III mRNA expression by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). NAD(P)H-dependent superoxide anion production was assayed as superoxide dismutase-inhibitable cytochrome c reduction. Intracellular formation of reactive oxygen species was assessed with 2',7'-dichlorofluorescein diacetate as fluorescent probe. RESULTS: Angiotensin II stimulated the collagen production, the collagen I and III content and mRNA expression in cardiac fibroblasts, and apocynin, a membrane NAD(P)H oxidase inhibitor, abolished this induction. Rotenone, allopurinol, indomethacin, nordihydroguiaretic acid, ketoconazole and nitro-L-arginine (inhibitors of mitochondrial NAD(P)H oxidase, xanthine oxidase, cyclooxygenase, lipoxygenase, cytochrome P450 oxygenase and nitric oxide synthase, respectively) did not affect the angiotensin II-induced collagen production. Angiotensin II increased the NAD(P)H-dependent superoxide anion production and the intracellular generation of reactive oxygen species in cardiac fibroblasts, and apocynin abrogated this rise. CONCLUSIONS: Our data show that in adult rat cardiac fibroblasts the membrane-associated NAD(P)H oxidase complex is the predominant source of superoxide anion and reactive oxygen species generation in angiotensin II-stimulated adult cardiac fibroblasts. Inhibition of this NAD(P)H oxidase complex with apocynin completely blocked the angiotensin II-stimulated collagen production, and collagen I and III protein and mRNA expression.

Precise subnanometer control of the position of a macro object by light pressure.

For the first time to the authors' knowledge, efficient control of the position of a macro object by coherent light was demonstrated. The minimal controllable mechanical displacement induced by the light pressure was 9 pm. No dependence of light pressure on wavelength in a broad wavelength range (405-1560 nm) was observed, as predicted by Maxwell's theory.

Refractive-index measurement of gases with a phase-shift keyed interferometer.

The presented new type of interferometer combines the principle of two-beam interferometry and the technique of phase-shift keying of holographic gratings. On the basis of the phase-shift keying technique, the interferometer employs two different geometries for the recording and the readout process. Two holographic Bragg gratings are recorded in transmission geometry and simultaneously read out in reflection geometry using a tunable IR laser. Both gratings have the same grating period but a relative phase shift. The wavelength of the readout beam is fitted to the Bragg condition for the gratings. Using a tunable IR laser for the readout process, we can measure the spectral transfer function of both combined gratings. The shape of the measured transfer function is extremely sensitive to the phase shift between the two gratings. We demonstrate an application of this method by the measurement of refractive-index variations of gases due to pressure changes of the gases. The achieved resolution with respect to the measurement of phase shifts is approximately 1/40 pi. We present experimental investigations on two kinds of gas (an inert gas and a gas composition) as well as an efficient numerical approach to simulate the transfer function for Bragg gratings with a phase shift. Furthermore, we present a method to increase the resolution based on the controlled manipulation of the transfer function.

Collagen production in cardiac fibroblasts during inhibition of aminopeptidase B.

OBJECTIVE: To determine whether the aminopeptidase B inhibitor, arphamenine A, could affect collagen production and expression in control and TGF-ss1-treated cardiac fibroblasts. DESIGN AND METHODS: Cardiac fibroblasts from passage 2 from normal male adult rats were cultured to confluency and incubated with and without 600 pmol/l TGF-ss1 for 2 days in serum-free Dulbecco's modified Eagle's medium and then incubated with 100 mol/l arphamenine A for 1 day in this medium with added ascorbic acid, ss-aminopropionitrile and titriated proline. Soluble collagen was measured in the conditioned medium and non-soluble collagen in the cell layer. Aminopeptidase activity was estimated by spectrophotometric determination of the liberation of p-nitroaniline from alanine- or arginine-p-nitroanilide. Matrix metalloproteinase (MMP) and lysyl oxidase activity were assayed in the conditioned medium. A semi-quantitative reverse transcriptase- polymerase chain reaction was used to examine the expression of lysyl oxidase and collagen type I and III. RESULTS: Arphamenine A dose-dependently inhibited basal and TGF-ss1-stimulated aminopeptidase activity. Arphamenine A reduced soluble and non-soluble collagen production in control and TGF-ss1-treated cardiac fibroblasts, while it decreased collagen type I and III expression only in TGF-ss1-treated fibroblasts. Lysyl oxidase, MMP-1 and MMP-2 activity were inhibited by arphamenine A in the conditioned media of control and TGF-ss1-treated cardiac fibroblasts. CONCLUSIONS: Our data show that the specific aminopeptidase B inhibitor, arphamenine A, reduces collagen production in cardiac fibroblasts and that this reduction is accompanied by a pronounced inhibition of lysyl oxidase.

Reversal of angiotensin II-stimulated collagen gel contraction in cardiac fibroblasts by aminopeptidase inhibition.

The purpose of this investigation was to determine whether aminopeptidase inhibition could affect the angiotensin II-stimulated collagen gel contraction in basal (control) and TGF-beta1-treated cardiac fibroblasts (or myofibroblasts). The tested aminopeptidase inhibitors were the broad range aminopeptidase inhibitor bestatin, the specific inhibitor of alanine aminopeptidase leuhistin, and the specific inhibitor of arginine aminopeptidase arphamenine A. Cardiac fibroblasts (from normal male adult rats) from passage 2 were cultured to confluency and incubated with(out) 400 pmol/L TGF-beta1 in Dulbecco Modified Eagle Medium (DMEM) with 10% fetal bovine serum (FBS). These fibroblasts were then further incubated in a floating collagen gel lattice with the tested products (angiotensin II, bestatin, leuhistin, or arphamenine A) for 3 days in DMEM without FBS. The contraction of the collagen gel lattice by cardiac fibroblasts was determined by measuring the gel volume with tritiated water. Aminopeptidase activity was estimated by spectrophotometric determination of the liberation of p-nitroaniline from alanine- or arginine-p-nitroanilide. Angiotensin II (100 nmol/L) reduced the gel volume in control and TGF-beta1-treated cardiac fibroblasts. The angiotensin II-stimulated collagen gel contraction in control and TGF-beta1-treated fibroblasts was almost completely reversed by leuhistin and arphamenine A (100 micromol/L). Bestatin (100 micromol/L) only partially inhibited the angiotensin II-stimulated collagen gel contraction in control fibroblasts, although it did not affect the angiotensin II-induced contraction in TGF-beta1-treated fibroblasts. In control and TGF-beta1-treated cardiac fibroblasts, 100 micromol/L leuhistin or arphamenine A only partially inhibited alanine aminopeptidase activity, whereas bestatin (100 micromol/L) completely inhibited the alanine aminopeptidase activity. Arginine aminopeptidase activity was only partially inhibited by leuhistin and arphamenine A at 100 micromol/L in control and TGF-beta1-treated fibroblasts. Bestatin, however, completely blocked the arginine aminopeptidase activity in control fibroblasts and only partially in TGF-beta1-treated fibroblasts at 100 micromol/L. Our data suggest that both alanine and arginine aminopeptidases are involved in the reversal of the angiotensin II-stimulated collagen gel contraction in control and TGF-beta1-treated cardiac fibroblasts or myofibroblasts.

Collagen production in cardiac fibroblasts during inhibition of angiotensin-converting enzyme and aminopeptidases.

OBJECTIVE: To determine whether lisinopril, an angiotensin-converting enzyme (ACE) inhibitor, and bestatin, an aminopeptidase inhibitor with broad specificity, could affect collagen production in control and transforming growth factor (TGF)-beta1-treated cardiac fibroblasts. DESIGN AND METHODS: Cardiac fibroblasts from passage 2 from normal male adult rats were cultured to confluency, incubated with or without 600 pmol/l TGF-beta1 for 2 days in serum-free Dulbecco's modified Eagle's medium and then incubated with the test products (lisinopril or bestatin) for 1 day in this medium with added ascorbic acid, beta-aminoproprionitrile and tritiated proline. Soluble collagen was measured in the conditioned medium and non-soluble collagen in the cell layer. ACE activity was measured fluorimetrically with hippuryl-histidyl-leucine as substrate, and DNA with the bisbenzimide dye, Hoechst 33,258. Aminopeptidase activity was estimated by spectrophotometric determination of the liberation of p-nitroaniline from alanine-p-nitroanilide. RESULTS: Lisinopril dose-dependently reduced ACE activity in control and TGF-beta1-treated cardiac fibroblasts. Bestatin inhibited the basal and TGF-beta1-stimulated aminopeptidase activity in a concentration-dependent manner. Lisinopril (10 micromol/l) decreased (P < 0.05) the production of soluble and non-soluble collagen in control cardiac fibroblasts. TGF-beta1 (600 pmol/l) increased (P < 0.05) the production of soluble and non-soluble collagen, and this effect was decreased (P < 0.05) by lisinopril. Bestatin (100 micromol/l) reduced (P < 0.01) the production of soluble collagen in control and TGF-beta1-treated cardiac fibroblasts, but did not affect the production of non-soluble collagen in these cells. CONCLUSIONS: Our data suggest that ACE and aminopeptidases are involved in the basal and TGF-beta1-stimulated production of collagen in adult rat cardiac fibroblasts in culture.

Effect of bestatin on angiotensin I-, II- and III-induced collagen gel contraction in cardiac fibroblasts.

OBJECTIVE: The purpose of this investigation was to determine whether the aminopeptidase inhibitor with broad specificity, bestatin, affects angiotensin I (Ang I)-, angiotensin II (Ang II)- or angiotensin III (Ang III)-stimulated collagen gel contraction in cardiac fibroblasts. DESIGN AND METHODS: Cardiac fibroblasts (from normal male adult rats) were cultured to confluency in Dulbeccos modified Eagles medium (DMEM) with 10% foetal bovine serum (FBS). These fibroblasts (100,000 cells) were then further incubated in a floating collagen gel lattice with the test products Ang I (1 micromol/L), Ang II (100 nmol/L), Ang III (100 nmol/L) and bestatin (100 micromol/L) for three days in DMEM without FBS. The area of the collagen gels embedded with cardiac fibroblasts was determined by a densitometric analysis. Aminopeptidase activity was estimated by spectrophotometric determination of the liberation of p-nitroaniline from alanine- or arginine-p-nitroanilide. RESULTS: Ang I, II and III stimulated (p<0.05) collagen gel contraction by 30.4+/-4.8 (SEM)%, 27.1+/-3.1% and 15.4+/-3.6% respectively. Ang I- and II-induced stimulation of collagen gel contraction was of the same order but more pronounced (p<0.05) than Ang III- stimulated collagen gel contraction. The Ang I-, II- and III-stimulated collagen contraction was reduced by bestatin. Bestatin, however, did not affect basal collagen gel contraction in cardiac fibroblasts. Bestatin dose-dependently inhibited the hydrolysis of arginine- and alanine-p-nitroanilide in cardiac fibroblasts. When a neutralising antibody to transforming growth factor TGF-b1 was added to the collagen gel simultaneously with the angiotensins, the stimulated collagen contraction was not affected. Beta-aminoproprionitrile, an inhibitor of lysyl oxidase, completely abolished basal as well as Ang I-, II- and III-stimulated collagen contraction in cardiac fibroblasts. RESULTS: Our data suggest that aminopeptidases are involved in the Ang I-, II- and III-induced stimulation of collagen contraction in cardiac fibroblasts.

Association between transforming growth factor-beta and hypertension.

Discordant findings are reported on the left ventricular transforming growth factor-beta(1) (TGF-beta(1)) mRNA levels in various rat models. Left ventricular TGF-beta(1) mRNA levels did not differ between spontaneously hypertensive rats (SHR) and normal rats, between deoxycorticosterone (DOCA)-salt and sham-operated hypertensive rats, but were increased in stroke-prone spontaneously hypertensive rats (SHRSP) and in post-myocardial infarction (MI) rats. Renal cortical TGF-beta(1) mRNA levels were, however, higher in DOCA-salt hypertensive rats. Angiotensin II subtype 1 receptor antagonism (AT(1)R) and angiotensin converting enzyme inhibition (ACEI) decreased left ventricular and vascular smooth muscle TGF-beta(1) mRNA levels in SHR and renal TGF-beta(1) mRNA in DOCA-salt hypertensive rats and in SHRSP. In post-MI rats ventricular TGF-beta(1) mRNA decreased by AT(1)R antagonism. In essential hypertensive patients, TGF-beta(1) protein as well as TGF-beta(1) mRNA levels are hyperexpressed. The TGF-beta(1) overproduction in hypertension can be attributed to various factors such as elevated angiotensin II, increased systemic blood pressure (BP) per se, increased fluid shear stress and a differential expression of TGF-beta(1) linked to DNA polymorphism in the promoter. The Arg(25) polymorphism in the TGF-beta(1) gene is associated with higher BP. A higher plasma TGF-beta(1) concentration is found in hypertensive patients with microalbuminuria and left ventricle hypertrophy. In these patients, AT(1)R antagonism and ACEI reduced these plasma TGF-beta(1) levels significantly.

Transforming growth factor-beta 1-mediated collagen gel contraction by cardiac fibroblasts.

OBJECTIVE: Myofibroblasts and transforming growth factor-beta(1) (TGF-beta(1)) are key elements of cardiac tissue fibrosis development. The aim of this study was to determine whether the ability of TGF-beta(1) to affect the contractile activity of cardiac fibroblasts depends on their differentiation into myofibroblasts. METHODS: Cardiac fibroblasts (from male adult Wistar rats) from passage two were cultured to confluency and incubated on a hydrated collagen gel with and without TGF-beta(1) (0, 20, 40, 100, 200, 400 or 600 pmol/L) for one, two and three days in a Dulbecco's Modified Eagle's Medium without foetal bovine serum. RESULTS: TGF-beta(1) dose-dependently increased the contraction of collagen gel mediated by cardiac fibroblasts, reaching a maximal effect at 100 pmol/L TGF-beta(1). TGF-beta(1) also stimulated 3(H)-thymidine incorporation and total protein content in cardiac fibroblasts in the collagen gel lattice. TGF-beta(1) dose-dependently induced an increase in beta-smooth muscle actin, a marker of myofibroblasts. The TGF-beta(1)-induced reduction of area of the collagen gel was negatively correlated to the TGF-beta(1)-evoked appearance of a-smooth muscle actin in the collagen gel matrix. CONCLUSION: Our data demonstrate that TGF-beta(1) increased the contractile activity of adult rat cardiac fibroblasts and their ability to differentiate into myofibroblasts. Because contractile activity was correlated with differentiation, the influence of TGF-beta(1) on cardiac fibroblast-induced collagen gel contraction might depend on the promotion of myofibroblast differentiation.