Noncontact test signal acquisition

An arrangement of electrostatic pickups for logic signals is described; this allows data over a wide range of repetition rates to be acquired from insulated wires or from insulation-covered printed circuits. Minimum coupling capacities are of the order of 1 pF and it is shown that 5 V pulses from 0.5 Hz to 5 MHz can be detected and reproduced. Preliminary results are also reported for an electrostatic pickup system for audio frequency analogue signals. Applications are suggested in high voltage DC isolation of analogue or digital circuits, noncontact computer bus couplers and diagnostic probes.     

Teichoic acid content in the cell wall of Actinomyces rimosus LST-118 in the process of ontogeny

Polymeric compounds of the cell walls of Act. rimosus were studied during the actinomycete growth. It was found that the content of teichoic acid decreased 2 times by the end of development of Act. rimosus, while content of glycane polymer remained approximately at the same level. The molar ratios of teichoic acid and glycopeptide glycane were determined.     

Masking of electrical by acoustic stimuli: behavioral evidence for tonotopic organization

When pure-tone acoustic masking stimuli of various frequencies were presented simultaneously with electrical stimuli applied to cochlear nucleus, only those maskers within a limited frequency range interfered with the detection of the electrical stimuli. The form of the masking functions obtained suggest that the electrical stimulus directly activated only a small population of neurons which were functioning in a tonotopic fashion.     

Mapping immunoreactive epitopes in the human peripheral nervous system using human monoclonal anti-GM1 ganglioside antibodies

A series of monoclonal IgM anti-GM1 ganglioside antibodies has been cloned from peripheral blood lymphocytes of patients with multifocal motor neuropathy and Guillain-Barré syndrome. In solid-phase immunoassay, the antibodies react with GMI, and also in differing degrees to the structurally related glycolipids asialo-GM1 (GA1) and GD1b. Here we describe the binding patterns of six human anti-GM I antibodies to epitopes within the human nervous system. Antibodies were observed to bind to motor neurons and spinal grey matter, dorsal and ventral spinal roots, dorsal root ganglion neurons, nodes of Ranvier, neuromuscular junctions and skeletal muscle. The distribution of immunoreactive epitopes, which included sensory structures, extended beyond those sites conventionally regarded as pathologically affected in anti-GM1 antibody-associated motor nerve syndromes. This undermines a model of disease pathogenesis based solely on antigen distribution. Factors other than the presence or absence of antigen, such as the local ganglioside topography, antibody penetration into, and pathophysiological vulnerability of a particular site may also influence the clinicopathological outcome of anti-GM1 antibody-mediated autoimmune attack.     

Intracochlear factors contributing to psychophysical percepts following cochlear implantation

Glycosyl-phosphatidylinositol (GPI) lipids have a structural role as protein anchors to the cell surface. In addition, they are implicated in hormone, growth factor and cytokine signal transduction. Their phosphodiesteric hydrolysis mediated by an activated phospholipase results in the generation of water soluble oligosaccharide species termed the inositol phosphoglycan (IPG). This product has been demonstrated to possess biological properties when added exogenously to cells mimicking the biological effects of a variety of extracellular ligands. This may be accomplished since IPG is generic for a family of closely related species which are released in a tissue-specific manner and additionally have cell-specific targets. Micro-organic synthesis has recently been able to shed new light on this topic by the introduction of defined oligosaccharide analogues of IPG for the assessment of their biological activity. These have complemented the findings observed with purified IPG from biological sources thus strengthening the belief that the GPI/IPG signalling system represents a truly novel aspect of transmembrane signalling.     

Clearance of Pneumocystis carinii cysts in acute P carinii pneumonia: assessment by serial sputum induction

STUDY OBJECTIVES: To determine the feasibility of repeat sputum induction in acute Pneumocystis carinii pneumonia (PCP) and to define the rate of clearance of P carinii cysts from the respiratory tract of HIV-seropositive patients with acute PCP. DESIGN: Prospective cohort evaluation. SETTING: University medical center. PARTICIPANTS: Twenty-four HIV-seropositive subjects with acute PCP. MEASUREMENTS: Sputum induction for P carinii 2, 3, 4, and 6 weeks after initial diagnosis, and follow-up for 1 year. RESULTS: Eighty-eight percent of subjects had residual cysts at 2 weeks, 76% at 3 weeks, 29% at 4 weeks, and 24% at 6 weeks postdiagnosis. A prior AIDS-defining illness (p = 0.033) or prior PCP (p = 0.004) predicted relapse within 6 months, but persistent cysts at 3 weeks did not; 8 of 16 sputum-positive subjects and 1 of 5 sputum-negative subjects experienced a relapse within 6 months (p = 0.34). Secondary prophylaxis with trimethoprim-sulfamethoxazole was associated with a reduced risk of relapse. CONCLUSIONS: Serial sputum induction coupled with direct fluorescent antibody staining is a feasible, noninvasive method of respiratory tract surveillance for the eradication of P carinii during and after acute PCP. Three-quarters of HIV-seropositive patients with acute PCP have persistent cysts in their lungs at the end of antimicrobial treatment, despite clinical recuperation, but only one quarter have residual cysts 6 weeks postdiagnosis. A prior AIDS-defining illness and prior PCP are positively associated, and subsequent trimethoprim-sulfamethoxazole prophylaxis is negatively associated, with relapse within 6 months, while persistent organisms at 3 weeks do not appear to be a significant predictor of relapse risk.