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Jerne’s network theory of the immune system is strongly supported by numerous findings that there are lymphocytic clones bearing receptors that recognize antigenic markers expressed on the receptors of other clones (1).

Most materials, and all biological materials, acquire an electrical charge when dispersed in polar media, for example, electrolyte solutions. This is so for simple ions, organic acids and bases, amino acids, proteins and microbial cells. The charge properties of such materials can be used in their separation. Three types of separation of which the essential features are charged materials, an applied electric field and an appropriate membrane are presented. These are electrodialysis, free-flow electrophoresis and electrofiltration. The basis of each process is described and the design of appropriate equipment outlined. Specific applications in the separation of biological materials are described.

Purpose of study: There is ongoing controversy as to the risk of paraplegia from segmental artery ligation during anterior spinal fusion. While somatosensory evoked potentials have been used to test indirectly for spinal cord ischemia after temporary segmental artery occlusion, the potential for a false-negative finding is high, because the SSEP is dorsal column mediated. The purpose of this study was to determine if transcranial electrical motor-evoked potentials (TCEMEPs) could provide a more sensitive, direct test for identifying nutrient-feeding segmental arteries that are critical to anterior spinal motor tract function before vessel ligation. Methods used: TCEMEPs (Digitimer, Ltd., Garden City, UK) were recorded from bilateral quadriceps, tibialis anterior and/or abductor hallucis muscles as well as from an upper extremity control muscle group, both before and 2 to 3 minutes after test occlusion of each candidate segmental artery. If postocclusion TCEMEP amplitudes did not change, the vessel was permanently ligated. If, however, response amplitude over one or more lower extremity muscles was diminished by more than 50%, the clamp was released until complete amplitude recovery. If on subsequent reclamping, TCEMEP amplitudes again diminished (more than 50%), no permanent ligation was performed. of findings: Significant TCEMEP changes after temporary vessel occlusion were noted in 8 (6.0%) of 150 pediatric patients in this series. In two patients, the TCEMEP changes were correlated with hypotension (MAP Relationship between findings and existing knowledge: TCEMEPs provide a rapid, valid and reliably sensitive technique for identifying segmental arteries that may be nutrient feeders to the anterior spinal cord. If ligated, such segmental vessels may predispose the patient to anterior spinal cord ischemic injury, particularly during a single-stage anterior-posterior spinal fusion for scoliosis correction. Overall significance of findings: These data suggest that, in select patients, there are segmental arteries that represent critical feeding vessels to the anterior spinal artery for maintenance of adequate spinal cord perfusion during the application of strong corrective spinal forces. Disclosures: Device or drug: Digitimer D-185 Multi-Pulse Motor Evoked Potential Stimulator. Status: investigational. Conflict of interest: No conflicts.

Nature 393, 663– 665 (1998) In Fig. 3, an incorrect file was plotted for the data in the inset for the isolated spheres (square symbols). This is now plotted correctly, together with a more informative caption. This correction does not affect the conclusions of our paper.

• Objective. —To report a case of thyroid storm that developed in a child with McCune-Albright syndrome after orthopedic surgery. The development of thyroid storm has not previously been described after surgery in a child. Design. —Descriptive case report. Setting. —Pediatric intensive care unit. Participant. —Patient with McCune-Albright syndrome who developed thyroid storm. Selection Procedures and Interventions. —Clinical features and treatment of thyroid storm are described. A highly sensitive immunochemiluminometric thyroid-stimulating hormone assay to help diagnose hyperthyroid states is also described. Conclusions. —Before all operative procedures, children at high risk for thyroid dysfunction, including patients with McCune-Albright syndrome, should be screened and observed closely for the development of thyroid storm. (AJDC. 1992;146:1099-1102)

The transparent disc electrode has been used to investigate three possible photogalvanic systems — the iron-thionine system and two iron-ruthenium systems. Results have been obtained for the photocurrent both in the steady state and for the modulated photocurrent produced when the light source is modulated. In the latter case the phase shift and amplitude of the photocurrent are measured as a function of the frequency of modulation. The results are in good agreement with the theoretical equation devised for the transparent rotating disc electrode, and the values of the rate constants obtained agree with those obtained by more conventional techniques such as stopped flow or flash photolysis. Moreover values are obtained for the overall quantum efficiency, φ, for the production of the electroactive species. For the ruthenium systems φ∼-1 but for the iron thionine system φ⋍0.8.

It has recently been demonstrated that the ζ potential of concentrated colloidal dispersions may be determined by measurement of the rate of electroosmosis at colloid occluded membranes. The present paper substantially extends the range of the technique in a study of dispersions of the clays kaolin and Fuller's earth at up to 1000 g liter − solids ( φ p = 0.4). It is found that the effective ζ potential decreases with concentration in both cases, an effect which is especially marked for Fuller's earth. This dependence correlates in a noteworthy manner with the rheological properties of the dispersions. Such measurement of the concentration dependence of ζ potential, which has previously received little attention, may well prove a useful probe for changes in the structure of complex dispersions.

A simple apparatus for the measurement of the rate of electro-osmosis at microporous membranes is described. This provides an effective method for the determination of the zeta-potential of the membranes. Occlusion of colloids in the voids of these highly porous membranes occurs readily, and is enhanced by electrophoretic deposition. Measurement of the rate of electro-osmosis at such colloid occluded membranes allows the determination of the zeta-potential of the colloid. These latter measurements give results which are dependent neither on the zeta-potential of the membrane nor on the membrane pore size (above a minimum critical value). Good comparison with conventional microelectrophoretic data is obtained over a wide pH range. This occluded membrane technique is most effective at colloid concentrations greater than 1 g/liter, a concentration range inaccessible to microelectrophoretic measurements. Formation and use of a colloid occluded membrane is less troublesome than the preparation of porous plugs for conventional streaming potential or electro-osmotic measurements.

Results are presented for the composition of the photostationary state in the iron—thionine photo-redox system as a function of the concentration of Fe(II) and Fe(III) and of the irradiance of the light. From these results the mechanism of the photo-redox system can be deduced. It is shown that depending on the conditions two of the possible six mechanisms are found. The implications for the efficient conversion of solar energy into electrical energy are discussed.

Bioelectrosynthesis is a novel approach to developing new routes for the synthesis of fine chemicals and pharmaceuticals which combines the speed and selectivity of enzymic catalysis with an electrode as the ultimate source of reducing or oxidizing power. The electrochemistries of the NAD + /NADH, FAD/FADH 2 , and FMN/FMNH 2 systems are used to illustrate some basic principles. Technical and economic factors are also considered.

The basis of two innovative electrolytic techniques for the combating of membrane fouling during cross-flow microfiltration is described. The first, which we have termed “in situ intermittent electrolytic membrane cleaning” or IIEMC, makes use of brief, intermittent electric field pulses to clean membranes without interruption of the separation process. Experimental studies of the filtration of dispersions of baker's yeast and titanium dioxide, chosen as model systems representing biological and inorganic process streams, show that this technique can improve overall membrane permeation rates by a factor of up to ten with only a modest electrical energy requirement. The second, which we have termed “in situ electrolytic membrane restoration” or IEMR, is very effective at restoring membrane water permeation rates under mild chemical conditions. Used in combination, these techniques may obviate the requirement for membrane backflushing and conventional chemical cleaning.

A general treatment is presented for photo-redox systems in which a one-electron redox couple reacts with a two-electron redox couple. It is demonstrated that there are six different mechanisms by which the system can react. Which mechanism is found depends not only on the concentrations of the different species but also on the irradiance of the light. The inter-relation of the different mechanisms and the implications for photogalvanic cells are discussed.

The kinetics of the iron-thionine system have been investigated using the transparent rotating disc electrode and flash electrolysis. Using the transparent disc electrode, from the results for the variation of photocurrent with rotation speed and irradiance, we can find the quantum efficiency for the production of semithionine, the efficiency for producing leucothionine from semithionine and the rate constant for the back reaction of leucothionine with Fe(III). This rate constant is also determined from the flash electrolysis experiments. The values of the kinetic parameters are found to be in good agreement with values determined by analysis of the photostationary state, flash photolysis and ac modulation at a transparent disc electrode. The relative merits of the different techniques for investigating photogalvanic systems are discussed.

Studies using ring-disc electrodes, cyclic voltammetry, optical absorption and X-ray photoelectron spectroscopy show that up to twenty monolayers of thionine can be irreversibly coated on to platinum or tin oxide electrodes. On such electrodes the electrode kinetics of the thionine-leucothionine couple are still reversible or quasi reversible. In contrast the reduction of Fe(III) is much slower on a coated electrode compared to a clean electrode. Koutecky-Levich plots show that there is a second potential-independent rate-limiting step. This blocking of the Fe(III) reduction means that the thionine coated electrode is the ideal electrode for a photogalvanic cell using the iron thionine system.

Myotonic dystrophy is a progressive multisystem disorder that may be inherited from either parent, although only children with affected mothers usually show the more severe congenital form of the condition; others are classified as having adult myotonic dystrophy. Since 1940, 29 patients with myotonic dystrophy (10 adult, 17 congenital, two unclassifed) have been followed at the Alfred I. duPont Institute. Treatment protocols have been established for the treatment of talipes equinovarus deformity commonly seen in the congenital form of myotonic dystrophy, as well as the progressive dropfoot gait more commonly seen in the adult form.