Turbulent heating in galaxy clusters brightest in X-rays.

The hot (10(7) to 10(8) kelvin), X-ray-emitting intracluster medium (ICM) is the dominant baryonic constituent of clusters of galaxies. In the cores of many clusters, radiative energy losses from the ICM occur on timescales much shorter than the age of the system. Unchecked, this cooling would lead to massive accumulations of cold gas and vigorous star formation, in contradiction to observations. Various sources of energy capable of compensating for these cooling losses have been proposed, the most promising being heating by the supermassive black holes in the central galaxies, through inflation of bubbles of relativistic plasma. Regardless of the original source of energy, the question of how this energy is transferred to the ICM remains open. Here we present a plausible solution to this question based on deep X-ray data and a new data analysis method that enable us to evaluate directly the ICM heating rate from the dissipation of turbulence. We find that turbulent heating is sufficient to offset radiative cooling and indeed appears to balance it locally at each radius-it may therefore be the key element in resolving the gas cooling problem in cluster cores and, more universally, in the atmospheres of X-ray-emitting, gas-rich systems on scales from galaxy clusters to groups and elliptical galaxies.

Preliminary Analysis of Capsicum Annuum L. Extracts.

The aim of this study was to investigate Capsicum Annuum L. ultrasonicated extracts and dry powder. The percentage of water, dry matter and ash were determined. FT-IR analysis confirmed the presence of important classes of secondary metabolites in the extracts and by GC-MS a large number of important pharmaceutical compounds were identified, including capsaicin.

Matrix metalloproteinases in the pathology of natural and bioprosthetic cardiac valves.

Degenerative dysfunction of cardiac valves may be accounted for by uncontrolled extracellular matrix degradation processes in which matrix metalloproteinases could play a major role. In this study, 24 pathologic human valves and 26 pericardial-derived bioprostheses were analysed for metalloproteinases by gelatin zymography. Compared to controls, human stenotic valves and bioprostheses explanted because of either calcifying or noncalcifying degeneration revealed three notable biochemical aspects: (1) an amplification in the levels of metalloproteinase 9 (gelatinase B), suggestive of its active role in valvular pathology; (2) minimal modifications in the gelatinolytic levels of metalloproteinase 2 (gelatinase A), indicative of a constitutive secretion; and (3) activation products derived from both gelatinase A and B. All gelatinolytic activities identified in pathologic specimens were inhibited in vitro by zinc and calcium chelators (captopril, doxycycline, dithiothreitol, and ethylenediaminotetraacetic acid), suggesting potential therapeutic approaches. High levels of beta-glucuronidase (a lysosomal marker enzyme for phagocytic cells) were found in human calcified stenotic valves and in ruptured and calcified pericardial-derived bioprostheses. Mononuclear recruitment was minimal to moderate in pathologic human valves, and in noncalcified ruptured bioprostheses infiltrating mononuclear cells were concentrated in large numbers at the cuspal free edge. These findings suggest the involvement of infiltrating phagocytic cells and putative common mechanisms in the degeneration of both the natural and the bioprosthetic valvular extracellular matrix (ECM).

Biochemical pathways of tissue degeneration in bioprosthetic cardiac valves. The role of matrix metalloproteinases.

Degeneration processes that affect bioprosthetic heart valves made from glutaraldehyde treated bovine pericardium are poorly understood. The present study undertook the identification and characterization of matrix metalloproteinases (MMPs) in extracts obtained from 28 pericardial derived bioprosthetic heart valves explanted at surgery. A lysosomal marker was used to assess the incidence of infiltrating extracellular matrix degrading cells. The major biochemical features that were associated with tissue degeneration and bioprosthetic heart valve failure were increased levels of MMP 9, high levels of beta-glucuronidase, and constant levels of active collagenase and MMP 2. The MMPs extracted from ruptured bioprostheses were inhibited by calcium chelators and zinc binding compounds. These data suggest that tissue failure, in addition to known mechanical and calcification related factors, may be contributed to by the intervention of proteolytic enzymes. A schematic working model was proposed that described the major biochemical pathways underlying tissue degeneration, starting from bioprostheses preparation and ending with clinical failure.

Matrix metalloproteinases and tissue valve degeneration.

Bioprosthetic heart valves have been used as replacements for diseased heart valves for over 30 years. More than 50% of bioprosthetic valves fail within 15 years because of structural deterioration. The role of proteolytic degradation, with particular reference to the matrix metalloproteinases (MMPs) in the degeneration of aortic bioprostheses, is appraised in this minireview. It is clear that both the intrinsic and host-derived proteolytic activities present in heart-valve bioprostheses may combine with mechanical stress to bring about valve failure.

Linear structures in the core of the Coma cluster of galaxies.

The hot x-ray-emitting plasma in galaxy clusters is predicted to have turbulent motion, which can contribute around 10% of the cluster's central energy density. We report deep Chandra X-ray Observatory observations of the Coma cluster core, showing the presence of quasi-linear high-density arms spanning 150 kiloparsecs, consisting of low-entropy material that was probably stripped from merging subclusters. Two appear to be connected with a subgroup of galaxies at a 650-kiloparsec radius that is merging into the cluster, implying coherence over several hundred million years. Such a long lifetime implies that strong isotropic turbulence and conduction are suppressed in the core, despite the unrelaxed state of the cluster. Magnetic fields are presumably responsible. The structures seen in Coma present insight into the past billion years of subcluster merger activity.

Complex effects of imatinib on spontaneous and oxytocin-induced contractions in human non-pregnant myometrium.

Human myometrium includes two important cell populations involved in its contractility: smooth muscle fibers and interstitial cells. The pacemaking mechanism is not yet identified, but it is possible that myometrial smooth muscle cells contract in response to a signal generated by c-kit positive interstitial cells. The aim of this study was to investigate the effects of imatinib as a c-kit receptor antagonist on the spontaneous or oxytocin (OT) induced contractions of human non-pregnant myometrium in vitro. Myometrial strips were obtained from non-pregnant women (reproductive age) undergoing hysterectomy for benign indications. The strips were suspended in organ baths for recording of isometric tension. Imatinib effects were assessed on spontaneous contraction and after preexposure to OT.Direct exposure of myometrial strips to imatinib inhibits both amplitude and frequency of contractions (80-320 µM) in a dose dependent manner. Amplitude reverted back to 90% of the baseline amplitude by consequent addition of imatinib (until 480 µM). Total inhibition of myometrial contraction was obtained after addition of OT 60 nM. If myometrium was pre-exposed to OT (320 nM), imatinib 80-160 µm increased amplitude, while decreasing frequency. These data provide evidence that telocytes may be involved as modulators of the spontaneous contractions of the non-pregnant human uterus, via a tyrosine-kinase independent signaling pathway.

Temperature-dependent structure of liquid water investigated by means of energy-dispersive x-ray diffraction and molecular dynamics simulations.

X-ray diffraction is investigated in the supercooled region (263-273 K) and, for comparison, at ambient conditions. By means of an energy-dispersive set-up coherent x-ray scattering cross sections within a wide range of momentum transfer values are monitored simultaneously using in-house laboratory equipment. The data are corrected for the energy-dependent detector response, geometric broadening effects, sample absorption and Compton scattering. The corrected diffraction curves are in good agreement with results from the Advanced Light Source (ALS). Additional comparisons with available literature data and with computer simulation results of different rigid water models are presented, relating the scattering intensities to the microscopic H-bond structure and dynamics.

Lysine-enhanced glutaraldehyde crosslinking of collagenous biomaterials.

Crosslinking of collagenous biomaterials currently employs the use of glutaraldehyde. The putative enhancement of glutaraldehyde crosslinking by lysine was investigated in three model systems: bovine pericardium, collagen membranes, and bovine serum albumin. Repetitive sequential treatment of bovine pericardium with glutaraldehyde and lysine and finally with formaldehyde produced a matrix which, by the two criteria used (shrinkage temperature and urea/SDS soluble collagen), was shown to be more highly crosslinked than pericardium fixed in glutaraldehyde alone. Essentially the same results were obtained when membranes prepared from pepsin-soluble pericardial collagen were subjected to sequential glutaraldehyde and lysine treatments, reaching shrinkage temperatures of more than 90 degrees C. Heart valves prepared from lysine-enhanced glutaraldehyde crosslinked bovine pericardium were tested in vitro in an accelerated fatigue tester and have been shown to behave satisfactorily after 300 million cycles. These additional crosslinks proved to be stable in saline at 37 degrees C. Studies on bovine serum albumin attempted to get an insight into the mechanisms of lysine enhancement of glutaraldehyde crosslinking by treating sequentially albumin with glutaraldehyde and lysine and analysis of the products by gel filtration and SDS-PAGE. These studies suggest that free amino groups exposed by proteins are initially reacted with glutaraldehyde and then bridged by the diamino compound (lysine) producing more extensive intermolecular crosslinking than glutaraldehyde alone.

Mapping of glutaraldehyde-treated bovine pericardium and tissue selection for bioprosthetic heart valves.

Glutaraldehyde-crosslinked bovine pericardium is widely used in bioprosthetic heart valve fabrication. In an attempt to set a scientific basis for more reproducible tissue selection, we produced and analyzed topographical maps of glutaraldehyde-treated bovine pericardium. Whole pericardia were divided into specific anatomical areas and their thickness was measured and mapped on templates. In each area, the suture holding power was determined in both parallel and perpendicular (to the base-apex line) directions; analyses of the tearing patterns in each fragment were used to evaluate predominant fiber orientation, and observations were confirmed by polarized light microscopy. Complete maps were superimposed graphically to aid in the selection of certain areas that would have known fiber orientation, high suture holding power, and suitable thickness. Our results describe regional heterogeneity of bovine pericardial structure and mechanical properties, specifically demonstrating variations in thickness, suture holding power, and collagen fiber orientation. Two areas of choice (representing about 35% of the total) were described as suitable for use in bioprosthetic heart valve fabrication.

Detection of remnant proteolytic activities in unimplanted glutaraldehyde-treated bovine pericardium and explanted cardiac bioprostheses.

The presence and activity of proteolytic enzymes has been investigated in vitro on soluble and insoluble preparations obtained from both unimplanted and implanted glutaraldehyde-treated bovine parietal pericardium. Using detection by colorimetric techniques, soluble preparations were shown to hydrolyze enzyme substrates that are characteristic for trypsin-like proteases, cathepsin-like proteases, and collagenase. As detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in gradient gels and gel filtration on Sepharose CL-6B, insoluble (pellet) preparations degraded denatured type I collagen in a time-dependent pattern, producing low-molecular-weight fragments. These activities were partially inhibited by phenylmethylsulfonyl fluoride, N-ethyl maleimide, soybean trypsin inhibitor, para-chloromercuribenzoic acid, or ethylenediaminetetraacetic acid, suggesting the presence of a heterogeneous enzymatic mixture. Insoluble preparations incubated with pure pericardial dermatan sulfate proteoglycan detached the glycosaminoglycan chains from their core protein carrier, producing a digestion pattern similar to Cathepsin C. These findings demonstrate the presence of active proteases in glutaraldehyde-fixed bovine pericardium per se and in explanted pericardial bioprosthetic cardiac valves, an additional factor that might contribute to intrinsic extracellular matrix degeneration in pericardial bioprosthetic devices.

Effects of cobalt-60 gamma-irradiation in association with prostaglandin E1 treatment on the cyclic AMP levels of some radiosensitive tissues.

The amounts of cyclic AMP in brain, liver and intestinal mucosa have been measured in rats, at constant intervals, up to 18 days after whole-body exposure to either a unique moderate dose (500 rd) or a unique lethal dose (750 rd) of cobalt-60 gamma-radiation in association with a preliminary intraperitoneally treatment with prostaglandin E1 (5 microgram/100 g body weight/day) during five days. The amounts of tissular cyclic AMP in these two experimental groups were compared with those obtained from control groups identically irradiated or treated with prostaglandin E1. The effects of gamma-irradiation and prostaglandin E1 treatment on the cyclic AMP levels were found to be quite specific in these organs, suggesting that they contain different adenyl cyclase-cyclic AMP-phosphodiesterase systems: a cerebral system which is influenced by both gamma-radiation and prostaglandin E1, a hepatic system which is "radioresistant" and an intestinal system which is not influenced by prostaglandin E1. When associated with gamma-radiation, this prostaglandin is capable, on the one hand, to annul the "radioresistance" of the hepatic cyclic AMP system and, on the other hand, to annul the "radiosensitivity" of the intestinal cyclic AMP system.

Administration of amantadine for the prevention of Hong Kong influenza.

The prophylactic effectiveness of amantadine against A2/Hong Kong influenza was investigated in the course of a double-blind trial in Brasov, Romania, during an epidemic due to the Hong Kong virus that started there in March 1969.Altogether 215 subjects were included in the trial; 112 received 100 mg of amantadine twice daily for 20 days and the remaining 103 received inert placebo tablets. Of the amantadine-treated group, 2 had clinical symptoms diagnosed as influenza (1 of these was a doubtful diagnosis), whereas 20 (1 doubtful) of the placebo group had such symptoms. No case with both clinical symptoms and serologically confirmed influenza (>/=4-fold increase in haemagglutination-inhibition titre) occurred among 77 amantadine-treated subjects for whom paired sera were available but there were 13 such cases among the 74 placebo subjects with paired sera. These differences are statistically highly significant. No serious side-effects were recorded.The authors conclude that amantadine was highly effective in preventing overt disease and discuss indications that suggest that it did not interfere with the development of immunity in persons treated during the incubation period.

[Studies of the influenza epidemic of January-March, 1974]. / Cercetari asupra epidemiei de gripa din perioada ianuarie-martie 1974

In an epidemiologic, clinical and viral study of several influenza foci in some urban districts of Romania during January-March 1974, 23 influenza virus B Hong-Kong 8/73 strains were isolated. The dynamics of HAI serum antibodies confirmed the viral diagnosis. The epidemic ran a slow course, affecting especially the 14-25 years age group and had an evident benign clinical aspect.

Virological study of some influenza outbreaks in the period January--March 1975.

The virological study of some influenza outbreaks recorded in Romania in the period Jnauary--March 1975 resulted in the isolation of 29 influenza A2 virus strains antigenically close to the strains A2/Port Chalmers 1/73 and A2/England 42/72. The non-homogeneous antigenic structure of the isolates suggests the possible formation of natural hybrids.