Secondary membranoproliferative glomerulonephritis due to hemolytic uremic syndrome: an unusual presentation

In vitro selection can be used to generate nucleic acid ligands (aptamers) to target molecules ranging in size and structure from cations to cells. However, the selection process is repetitive and time-consuming. We have automated a protocol for in vitro selection using an augmented Beckman Biomek 2000 pipetting robot. The automated selection procedure requires the integration of four devices and the optimization of four molecular biology methods, and is one of the most complex automated protocols attempted to date. Initial attempts at selection yielded robust replication parasites, but optimization of the automated selection procedure suppressed the emergence of these parasites and led to the selection of true nucleic acid ligands. Automated selection can now be used to generate nucleic acid aptamers in days rather than weeks or months.     

Synthesis of polyribonucleotide chains from the 3'-hydroxyl terminus of oligodeoxynucleotides by Escherichia coli primase

Escherichia coli primase synthesizes RNA primers on DNA templates for the initiation of DNA replication. The sole known activity of primase is to catalyze synthesis of short RNA chains de novo. We now report a novel activity of primase, namely that it can synthesize RNA from the 3'-hydroxyl terminus of a pre-existing oligodeoxynucleotide. The oligonucleotide-primed synthesis of RNA by primase occurs in both of the G4oric-specific priming system and the dnaB protein associated general priming system. This priming reaction of primase is verified by a number of biochemical methods, including inhibition by modified 3'-phosphate of oligonucleotides and deoxyribonuclease I and ribonuclease H cleavages. We also show that the primed RNA is an effective primer for the synthesis of DNA chain by E. coli DNA polymerase III holoenzyme. The significance of this finding to primases generating multimeric length RNA is discussed.     

Pulmonary vein stenosis after catheter ablation of atrial fibrillation

BACKGROUND: This report describes the complication of pulmonary vein stenosis with resultant severe pulmonary hypertension that developed in 2 patients after successful catheter ablation of chronic atrial fibrillation. METHODS AND RESULTS: Three months after successful catheter ablation of atrial fibrillation, both patients developed progressive dyspnea and pulmonary hypertension. Both were found to have severe stenosis of all 4 pulmonary veins near the junction with the left atrium. Balloon dilation of the stenotic pulmonary veins was performed in these patients, with improvement in dyspnea and pulmonary hypertension. CONCLUSIONS: The complication of pulmonary vein stenosis is potentially life-threatening, and the application of radiofrequency current within the pulmonary veins with standard catheter technology should be avoided. This complication can be treated with balloon dilation, although the long-term course is unknown.     

A note on the stability of CSDT methods for solving parabolic equations

In this note we study the stability aspects of CSDT methods for solving parabolic partial differential equations. We define two types of stability and discuss the stability of various CSDT methods.     

Crosstalk Loss Requirements for PCM Transmission

We present in this paper a unified approach to the crosstalk interference problem arising in PCM transmission on paired cables. For bipolar signaling, and three types of commonly used channel shaping, viz., cosine, raised cosine, and Gaussian, we present the minimum average near-end crosstalk (NEXT) and far-end crosstalk (FEXT) loss requirements at any transmission rate as a function of repeater spacing and number of interfering pairs so as to meet a desired error rate objective. This will aid in indicating if new cables need to be developed for a proposed rate of transmission or, for a given cable, the error margin available for degradations other than crosstalk can be readily determined. Extension to other coding schemes is indicated, and crosstalk compatibility is examined for mixedTsystems, such asT1,T1C, andT2. Graphical results are presented to readily aid in system design of anyTcarrier with repeater spacings up to 70 dB.     

“Meandering” Effects on the Diffusion of Continuous Dye Plumes in Coastal Currents

Experimental data on the diffusion of fluorescent dye plumes were obtained in the nearshore zone of the Great Lakes. The transport and diffusion of continuous dye plumes may be studied either in a frame of reference moving with the centre of gravity of the plume or in a frame of reference fixed to the stationary source. Conventionally, the former is referred to as “relative” diffusion and the latter as “absolute” diffisuion. The inter-link between the two concepts is explained by the random movements of the centre of gravity of the diffusing dye plume usually referred to as the “meandering”.In the past, experimental data from continuous dye plumes in coastal currents have been used to study “relative” diffusion, neglecting the random movements of the centre of gravity. In reality, however, “meandering” appears to be a more efficient agency than “relative” diffusion from the practical point of view of dispersing effluents over larger volume of the water body.In the present analysis, particular attention is given to delineate the two component physical processes of “relative” diffusion and “meandering” diffusion, by extended sampling of the dye plume to cover time scales of both the processes. Calculated horizontal eddy diffusivity K_y in “absolute” diffusion is greater by a factor of 2 as compared to “relative” diffusion. Very high peak/mean concentration ratios observed as the centre of the plume are a direct result of “meandering” due to large scale turbulent eddies.