Magnesium deficiency enhances oxidative stress and collagen synthesis in vivo in the aorta of rats

Magnesium deficiency has been shown to produce vascular lesions in experimental animals, but the underlying mechanisms of vascular injury are not clear. It has been reported that in rodents, magnesium deficiency enhances circulating levels of factors that promote free radical generation and are mitogenic. In pursuance of these observations, the present study tested the hypothesis that magnesium deficiency may enhance oxidative stress and trigger an accelerated growth response in vivo in the aorta of rats. Oxidative stress was evaluated in terms of levels of thiobarbituric acid-reactive substances in the serum and aorta and activity of superoxide dismutase and catalase in the aorta; fractional rates of collagen synthesis were assessed using [3H]-proline. Serum and tissue levels of magnesium and calcium were determined by atomic absorption spectrophotometry. The present study demonstrated for the first time that magnesium deficiency significantly (P < 0.001) increases levels of thiobarbituric acid-reactive substances in the aorta of rats. Other changes in the aorta of animals on the Mg-deficient diet included a significant reduction (54%, P < 0.001) in the activity of superoxide dismutase and catalase (37%, P < 0.01) and a 19% increase in net fractional rates of collagen synthesis (P < 0.05). While serum magnesium was significantly reduced in these animals (P < 0.001), aortic tissue levels of magnesium in these animals remained unaltered throughout the duration of the study, suggesting the existence of other control mechanisms, apart from reduced tissue levels of magnesium, mediating the observed effects. These findings suggest that magnesium deficiency may trigger a wound healing response, involving oxidative injury and growth stimulation, in the vascular system.     

The HHIRF supersonic gas jet target facility

We describe a supersonic gas jet target built for studying reactions induced by heavy ions with high energy resolution. The device produces very localized high density gas jets in a near vacuum environment and is presently installed in the scattering chamber of a magnetic spectrograph at the ORNL HHIRF. With a 100 MeV ¹⁶O beam collimated to a size of approximately 1 mm² at the target, image sizes of 0.42 mm have been obtained at the focal plane of the spectrograph with a solid angle of 2.4 msr and target densities of 15–30 μg/cm².     

Parallelizing OODBMS traversals: a performance evaluation

In this paper we describe the design and implementation of ParSets, a means of exploiting parallelism in the SHORE OODBMS. We used ParSets to parallelize the graph traversal portion of the OO7 OODBMS benchmark, and present speedup and scaleup results from parallel SHORE running these traversals on a cluster of commodity workstations connected by a standard ethernet. For some OO7 traversals, SHORE achieved excellent speedup and scaleup; for other OO7 traversals, only marginal speedup and scaleup occurred. The characteristics of these traversals shed light on when the ParSet approach to parallelism can and cannot be applied to speed up an application. Edited by Henry F. Korth and Amith Sheth. Received November 1994 / Accepted March 20, 1995     

Cell adhesion and growth on synthetic hydrogel beads

Hydrolysed poly(methyl methacrylate) microspheres with carboxyl residues distributed throughout the matrix were tested for their ability to support cell adhesion and growth. Cell growth as determined by protein content, phase contrast and scanning electron microscopy showed that these microspheres are growth-supportive. Further, preliminary experiments pointed to their usefulness in microcarrier culture.     

Histone Methylation Regulation in Neurodegenerative Disorders

Advances achieved with molecular biology and genomics technologies have permitted investigators to discover epigenetic mechanisms, such as DNA methylation and histone posttranslational modifications, which are critical for gene expression in almost all tissues and in brain health and disease. These advances have influenced much interest in understanding the dysregulation of epigenetic mechanisms in neurodegenerative disorders. Although these disorders diverge in their fundamental causes and pathophysiology, several involve the dysregulation of histone methylation-mediated gene expression. Interestingly, epigenetic remodeling via histone methylation in specific brain regions has been suggested to play a critical function in the neurobiology of psychiatric disorders, including that related to neurodegenerative diseases. Prominently, epigenetic dysregulation currently brings considerable interest as an essential player in neurodegenerative disorders, such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), Amyotrophic lateral sclerosis (ALS) and drugs of abuse, including alcohol abuse disorder, where it may facilitate connections between genetic and environmental risk factors or directly influence disease-specific pathological factors. We have discussed the current state of histone methylation, therapeutic strategies, and future perspectives for these disorders. While not somatically heritable, the enzymes responsible for histone methylation regulation, such as histone methyltransferases and demethylases in neurons, are dynamic and reversible. They have become promising potential therapeutic targets to treat or prevent several neurodegenerative disorders. These findings, along with clinical data, may provide links between molecular-level changes and behavioral differences and provide novel avenues through which the epigenome may be targeted early on in people at risk for neurodegenerative disorders.     

Selection of Gravity Separators for the Beneficiation of the Uljin Tin Ore

Gravity separation is typically used in the beneficiation of tin ores as the density difference between the valuable and associated gangue minerals is significant. In the present investigation, a cassiterite sample collected from the Uljin deposit in South Korea has been subjected to different gravity separators to evaluate the separation efficiency. The selection of gravity units has been made based on performance evaluation following heavy liquid separation and assessment of grade/recovery curves and Tromp curve methods. In addition, a gravity separation index (GSI) has been proposed that is simpler than other methods for assessing the performance of gravity separators.     

On Using Twisted-Ring Counters for Test Set Embedding in BIST

We present a novel built-in self-test (BIST) architecture for high-performance circuits. The proposed approach is especially suitable for embedding precomputed test sets for core-based systems since it does not require a structural model of the circuit, either for fault simulation or for test generation. It utilizes a twisted-ring counter (TRC) for test-per-clock BIST and is appropriate for high-performance designs because it does not add any mapping logic to critical functional paths. Test patterns are generated on-chip by carefully reseeding the TRC. We show that a small number of seeds is adequate for generating test sequences that embed complete test sets for the ISCAS benchmark circuits.Instead of being stored on-chip, the seed patterns can also be scanned in using a low-cost, slower tester. The seeds can be viewed as an encoded version of the test set that is stored in tester memory. This requires almost 10X less memory than compacted test sets obtained from ATPG programs. This allows us to effectively combine high-quality BIST with external testing using slow testers. As the cost of high-speed testers increases, methodologies that facilitate testing using slow testers become especially important. The proposed approach is a step in that direction.     

Quantification of Antioxidants in Medicinal Plants and Foodstuffs Using Ce(IV) with Indigo Carmine as Chromogenic Probe

A simple, novel, sensitive and diversely applicable antioxidant assay method has been developed for the determination of total antioxidant capacity of some foodstuffs and medicinal plants. The method is based on the oxidation of antioxidants by a known amount of Ce(IV) sulphate under slightly acidic medium and subsequently allowing the unreacted Ce(IV) to react with a known amount of Indigo Carmine dye followed by measuring the unreacted blue-coloured Indigo Carmine dye solution at λ _max = 610 nm at room temperature. The antioxidant power was evaluated in terms of trolox equivalent antioxidant capacities and compared with those of ferric-reducing antioxidant power (FRAP–1.10 phenanthroline), Cu(II) reduction assay using bathocuproinedisulfonic acid disodim salt and 2, 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid methods. A good correlation (R ² = 0.926) was found with the classical spectrophotometric FRAP assay. The proposed method is reproducible and successfully applied to assess the total antioxidant capacities in foodstuffs, vegetables and medicinal plants. The obtained results were compared with reference methods. Interference from other substances was also studied.