silicon and Hypersensitivity

A protein concentration measurement system with two-port flexural plate-wave (FPW) biosensors using a frequency-shift readout technique is presented in this paper. The proposed frequency-shift readout method employs a peak detecting scheme to measure the amount of resonant frequency shift. The proposed system is composed of a linear frequency generator, a pair of peak detectors, two registers, and a subtractor. The frequency sweep range of the linear frequency generator is limited to 2 MHz to 10 MHz according to the characteristics of the FPW biosensors. The proposed frequency-shift readout circuit is carried out on silicon using a standard 0.18 μm CMOS technology. The sensitivity of the peak detectors is measured to be 10 mV. The power consumption of the proposed protein concentration measurement system is 48 mW given a 0.1 MHz system clock.

Topics: Biosensing Techniques; Electric Conductivity; Electrodes; Equipment Design; Gold; Humans; Hypersensitivity; Immunoglobulin E; Metals; Microscopy, Fluorescence; Oscillometry; Proteins; Sensitivity and Specificity; Silicon; Sulfhydryl Compounds

The authors present a case of a patient with an abdominal CSF pseudocyst that resulted from an allergic reaction to silicone. The patient underwent repair surgery of the meningomyelocele associated with the Chiari II malformation, and the V-P shunt was instituted at 6 months of age. A formation of the abdominal CSF pseudocyst and the consequent shunt malfunction were observed 40 days after the V-P shunt. An increase in the number of the peripheral eosinophils and serum immunoglobulin E (IgE), and an infiltration of eosinophils in the specimen harvested from the pseudocyst wall suggested an allergic reaction as the cause of the pseudocyst. A sixth operation to revise the V-P shunt was performed using the shunt system made of "extracted silicone", which was produced extracting the allergic substances.. The serum IgE was normalized after surgery and the abdominal CSF pseudocyst has not recurred for 22 months.

Topics: Abdomen; Cerebrospinal Fluid Shunts; Cysts; Eosinophils; Humans; Hydrocephalus; Hypersensitivity; Infant; Leukocytes; Male; Silicon; Staining and Labeling; Tomography, X-Ray Computed

Determination of the ability of a medical device to interact with the immune system currently involves assessment of the immunogenic potential and biocompatibility of the device or an extract of the device. However, implants are often in the body for extended periods of time and/or are placed by a surgical procedure that in and of itself will generate an acute inflammatory response. This symposium discussed studies that have been performed to evaluate the immunogenicity of various devices consisting of several different compositions (i.e., silicone, metals, and latex) in contact with different anatomical sites, the ability of a device to modulate an inflammatory response generated by a surgical procedure or trauma, and the response of the body to a material left in place for extended periods of time. This symposium brought together scientists from many different disciplines to begin to identify and fill in the gaps in this area.

Topics: Animals; Biocompatible Materials; Equipment and Supplies; Humans; Hypersensitivity; Immunity, Cellular; Inflammation; Latex; Materials Testing; Prostheses and Implants; Silicon; Toxicity Tests

This study aims to evaluate the influence of the anodic potential on metal-components dissolution from dental alloys and is intended to serve as an aid in the investigation of dental metal eruption (metal allergy). In the experiments, anodic potentials were applied electrochemically to various dental alloys in a 0.9% NaCl solution. Thereafter amounts of metal-component dissolution were measured by means of atomic absorption spectrophotometry. In addition, relations between metal-component dissolution and electrochemical characteristics (anodic polarization and charge transfer calculated from current density-time transients) were considered.. 1. Breakdown potentials determined on the basis of anodic polarization profiles agreed with potentials of remarkable increase in component dissolution. 2. Current density-time transients gave good indications of alloys' corrosion tendencies. Correlations between charge transfer and total amounts of metal-component dissolution were comparatively good. 3. Metal-component dissolutions in various alloys at fixed anodic potentials 1) Cu and Zn were found to dissolve slightly from gold alloys (types II and IV) at potentials above 200 mV (vs SCE). 2) Ag, Pd, Cu, and Zn were found to dissolve from the Ag-Pd-Cu-Au alloy at potentials above 100 mV. A comparatively large amount of Zn was released at low potentials. Amounts of Ag and Cu dissolution increased rapidly at 300 mV and 500 mV respectively. Although traces of it were detectable at low potentials, dissolution of Pd increased remarkably at 500 mV. 3) Ag, In, and Zn were found to dissolve from the Ag-In-Zn alloy at potentials above O mV. Amounts of In and Zn dissolution increased above 20 mV. The increase was especially remarkable in the case of In. 4) Sn and Zn were found to dissolve from the Ag-Sn-Zn alloy at potentials above -200 mV; Ag dissolved from the same alloy at potentials above 100 mV. Amounts of Sn and Zn dissolution increased at potentials above 100 mV. This was especially true in the case of Sn. 5) Ni, Cu and Si were found to dissolve from the soft type Ni-Cr alloy (9.0 wt% Cr) at potentials above -100 mV. Cr, Mn, and Fe dissolved from the same alloy at potentials above 0 mV; and Co at potentials above 200 mV. Metal-component dissolution was greater in the case of this alloy than in those of all the other alloys used in this study. A considerable amount fo Ni was released at 0 mV.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Chromium Alloys; Copper; Dental Alloys; Electrochemistry; Humans; Hypersensitivity; Indium; Iron; Manganese; Molybdenum; Nickel; Palladium; Silicon; Silver; Spectrophotometry, Atomic; Zinc

Topics: Adolescent; Aluminum; Child; Child, Preschool; Eczema; Humans; Hypersensitivity; Infant; Prurigo; Silicon; Skin Diseases