Effect of leflunomide on the peripheral nerves in rheumatoid arthritis.

BACKGROUND: The objective of this study was to determine the neurophysiological effects of leflunomide on peripheral nerves in rheumatoid arthritis. METHODS: We conducted a prospective cohort trial of 32 patients with rheumatoid arthritis with 16 patients receiving leflunomide treatment and 16 receiving other disease-modifying anti-rheumatic drug therapies. Clinical, laboratory and neurophysiological measurements were used to determine the presence of a peripheral neuropathy in these patients at study entry and then after a further 3 and 6 months. RESULTS: Fifty-four per cent of the leflunomide group and 8% of the control group had an increase in their neuropathy symptom score 6 months into the study (P = 0.01). No correlation was found between the electrophysiological findings and the clinical symptoms. There was no significant difference between the two groups in upper and lower limb sensory and motor amplitudes and conduction velocities recorded at 3 and 6 months. One patient developed both clinical and neurophysiological evidence of a peripheral neuropathy 5 months into the study that improved after cessation of leflunomide therapy and cholestyramine washout. CONCLUSION: After 6 months of exposure we found that leflunomide was associated with an apparent increase in the clinical symptoms of peripheral neuropathy in patients with rheumatoid arthritis. These symptoms did not correlate with neurophysiological studies.

Asynchronous transfer mode distribution network by use of an optoelectronic VLSI switching chip.

We describe a new optoelectronic switching system demonstration that implements part of the distribution fabric for a large asynchronous transfer mode (ATM) switch. The system uses a single optoelectronic VLSI modulator-based switching chip with more than 4000 optical input-outputs. The optical system images the input fibers from a two-dimensional fiber bundle onto this chip. A new optomechanical design allows the system to be mounted in a standard electronic equipment frame. A large section of the switch was operated as a 208-Mbits/s time-multiplexed space switch, which can serve as part of an ATM switch by use of an appropriate out-of-band controller. A larger section with 896 input light beams and 256 output beams was operated at 160 Mbits/s as a slowly reconfigurable space switch.

Shuffle-equivalent interconnection topologies based on computer-generated binary-phase gratings.

Several different shuffle-equivalent interconnection topologies that can be used within the optical link stages of photonic-switching networks are studied. These schemes include the two shuffle, the two banyan, and the segmented two shuffle, which can be used to interconnect two-input, two-output switching nodes. The schemes also include the four shuffle and the four banyan, which can be used to interconnect four-input, four-output switching nodes. (Note: The segmented two shuffle and the four banyan are novel interconnection topologies that were developed to satisfy some of the constraints of free-space digital optics). It is shown that each of these interconnection topologies can be implemented by the use of relatively simple imaging optics that contain space-invariant computer-generated binaryphase gratings. The effects of node type and interconnection topology on the laser power requirements and the optical component complexity within the resulting systems are also studied. The general class of networks nown as extended generalized shuffle networks is used as a baseline for the analysis. It is shown that (2, 1, 1) nodes and (2, 2, 2) nodes connected by two-banyan interconnections can produce power-efficient and cost-effective systems. The results should help identify the architectural trade-offs that exist when a node type and an interconnection topology are selected for implementation within a switching system based on free-space digital optics.

Free-space photonic switching architectures based on extended generalized shuffle networks.

A new class of networks that is well suited for free-space photonic switching applications is described. These networks are known as extended generalized shuffle networks. It is shown that these networks can provide low blocking probabilities while requiring low hardware costs. In fact, if sufficient hardware is added to these networks, they become strictly nonblocking networks (with blocking probabilities equal to zero). The hardware cost of an extended generalized shuffle network can be modified to yield any desired blocking probability, so cost-effective designs are possible. In addition, it is shown that these networks are extremely fault tolerant, and they can also be designed to have high system availabilities. Because the networks can use various types of interconnections to connect the nodes and because the nodes can have various types of functionality, these networks also provide high degrees of flexibility that can be used to optimize a free-space photonic design. The design of extended generalized shuffle networks based on a particular node type that is easy to implement with symmetric self-electro-opticeffect devices is studied.