Indications for Cardiac Pacing

The indications for implantation of a long-term cardiac pacemaker consist of two major categories--the prevention of Stokes-Adams attacks and an inadequate cardiac output caused by a slow ventricular rate

Historical Development of Cardiac Pacing

I would like to discuss the development and historical aspects of cardiac pacemaking from a personal point of view, presented as it appeared to me over the years. This approach is biased, selective, and incomplete, but I think as informative as I can make it

Sorption of Yttrium and the Rare Earth Elements on the Marine Macroalga Ulva lactuca

Trace metal interactions with organic matter are relatively poorly understood, though organic matter is ubiquitous in aquatic environments and likely instrumental in controlling metal geochemistry. To better understand the mechanisms underlying metal interactions with organic substrates, sorption of Yttrium and the Rare Earth Elements (YREEs) on Ulva lactuca, a marine macroalga, was studied in batch laboratory experiments at different ionic strengths over a large pH range (2.7 - 8.5). At all ionic strengths and experimental pH values, colloid-bound YREEs make up a substantial portion of sorbed metals as described by a two-site Langmuir model, which has implications for bioremediation and metal sorption studies. YREE sorption on U. lactuca can be modeled as a function of pH with a three-site non-electrostatic surface complexation model, and patterns of conditional YREE complexation constants were used to determine possible identities of metal-complexing functional groups

Gene expression in skeletal muscle of coronary artery disease patients after concentric and eccentric endurance training

Low-intensity concentric (CET) and eccentric (EET) endurance-type training induce specific structural adaptations in skeletal muscle. We evaluated to which extent steady-state adaptations in transcript levels are involved in the compensatory alterations of muscle mitochondria and myofibrils with CET versus EET at a matched metabolic exercise intensity of medicated, stable coronary patients (CAD). Biopsies were obtained from vastus lateralis muscle before and after 8weeks of CET (n=6) or EET (n=6). Transcript levels for factors involved in mitochondrial biogenesis (PGC-1α, Tfam), mitochondrial function (COX-1, COX-4), control of contractile phenotype (MyHC I, IIa, IIx) as well as mechanical stress marker (IGF-I) were quantified using an reverse-transcriptase polymerase chain reaction approach. After 8weeks of EET, a reduction of the COX-4mRNA level by 41% and a tendency for a drop in Tfam transcript concentration (−33%, P=0.06) was noted. This down-regulation corresponded to a drop in total mitochondrial volume density. MyHC-IIa transcript levels were specifically decreased after EET, and MyHC-I mRNA showed a trend towards a reduction (P=0.08). Total fiber cross-sectional area was not altered. After CET and EET, the IGF-I mRNA level was significantly increased. The PGC-1α significantly correlated with Tfam, and both PGC-1α and Tfam significantly correlated with COX-1 and COX-4mRNAs. Post-hoc analysis identified significant interactions between the concurrent medication and muscular transcript levels as well as fiber size. Our findings support the concept that specific transcriptional adaptations mediate the divergent mitochondrial response of muscle cells to endurance training under different load condition and indicate a mismatch of processes related to muscle hypertrophy in medicated CAD patient

Unusual Loop-Sequence Flexibility of the Proximal RNA Replication Element in EMCV

Picornaviruses contain stable RNA structures at the 5′ and 3′ ends of the RNA genome, OriL and OriR involved in viral RNA replication. The OriL RNA element found at the 5′ end of the enterovirus genome folds into a cloverleaf-like configuration. In vivo SELEX experiments revealed that functioning of the poliovirus cloverleaf depends on a specific structure in this RNA element. Little is known about the OriL of cardioviruses. Here, we investigated structural aspects and requirements of the apical loop of proximal stem-loop SL-A of mengovirus, a strain of EMCV. Using NMR spectroscopy, we showed that the mengovirus SL-A apical loop consists of an octaloop. In vivo SELEX experiments demonstrated that a large number of random sequences are tolerated in the apical octaloop that support virus replication. Mutants in which the SL-A loop size and the length of the upper part of the stem were varied showed that both stem-length and stability of the octaloop are important determinants for viral RNA replication and virus reproduction. Together, these data show that stem-loop A plays an important role in virus replication. The high degree of sequence flexibility and the lack of selective pressure on the octaloop argue against a role in sequence specific RNA-protein or RNA-RNA interactions in which octaloop nucleotides are involved

A Real-Time Knowledge Scheme for Sensory-Controlled Robot Assembly Tasks

In the field of assembly automation with industrial robots the research on the application of artificial intelligence techniques is getting increasing importance. This paper describes the hierarchical structure of a knowledge—based sensory-controlled robot assembly system under development which is capable to plan and execute assembly tasks under real—time requirements. The hybrid knowledge representation scheme combining the rule—based and object—oriented approach to represent the assembly domain—specific knowledge is discussed. Furtheron, the knowledge processing concept based upon the representation scheme is explained. A first prototype of the system has been implemented in a real robotic test—bed. Several peg/hole part mating sequences validated the capability of the system to execute assembly tasks in an uncertain environment using sensory information

Експортно­імпортні операції в Чернігівській губернії на початку ХХ ст.

У статті на основі маловідомих фактів досліджується організація зовнішньої торгівлі в Чернігівській губернії Російської імперії на початку ХХ ст. Показані основні екпортно-імпортні операції, особливості економічного розвитку регіону.В научной статье на основании использования неизвестных ранее фактов исследуется организация внешней торговли в Черниговской губернии Российской империи в начале ХХ века. Показаны основные экспортно-импортные операции и особенности экономического развития региона.In scientific article author research the special organization of foreign trade in Chernigov’s region of Russian empire in the beginning of 20 century. Export-import operations and economic development had illustration in this work