Duplex scanning for noninvasive assessment of both carotid luminal diameter and atheromatous plaque morphology.

The value of Duplex scanning in 50 consecutive patients with symptomatic carotid stenosis was evaluated. Compared with contrast arteriography, the sensitivity of Duplex scanning, for a greater than 50% internal carotid diameter reduction, was 90% (66/73) with a specificity of 96% (26/27). The overall agreement between Duplex and contrast arteriography as measured by the Kappa value was K = 0.561. One of the 13 arteries felt to be occluded on Duplex scanning was radiologically found to be patent. Excluding the six normal and 13 occluded arteries, 81 carotid plaques were defined as either heterogeneous, suggestive of intraplaque hemorrhage or as homogeneous. Twenty-four of the 32 asymptomatic cerebral hemispheres were associated with ipsilateral homogeneous plaques, while 30 of the 49 symptomatic hemispheres had heterogeneous plaques in the ipsilateral carotid, (p less than 0.001). This study confirms the accuracy of duplex scanning in detecting internal carotid stenosis as well as in identifying plaques which are morphologically heterogeneous and more likely to be associated with ipsilateral cerebral hemispheric symptoms.

Detection of bullet residue in bone using proton-induced X-ray emission (PIXE) analysis.

External beam proton-induced X-ray emission (PIXE) analysis has been used to verify the presence of lead in the finger bone of a murder victim. The deceased, who had been buried several years, was known to have suffered a bullet wound to his right hand several years before death. X-ray radiographs of the right second proximal phalanx revealed the possible presence of metal fragments below the surface of the bone. To verify the presence of lead in a nondestructive manner, the bone was scanned with a 1.5-MeV proton beam. PIXE analysis showed that lead was present only in the vicinity of the fragments previously detected in the radiographs. A study of gunshot residue in bone shows that the distribution of lead around the bullet hole is independent of the firing distance for distances greater than 0.6 m.

Ultraviolet light induces binding of antibodies to selected nuclear antigens on cultured human keratinocytes.

Antibodies which bind to different nuclear antigens in tissue sections or in permeabilized cell cultures are useful markers of subsets of connective tissue disease, especially of lupus erythematosus (LE), but whether these antibodies are able to react with these intracellular sequestered antigens in vivo and cause immunologic tissue damage has been a matter of much debate. We report experiments which show that ultraviolet light-irradiated, cultured human keratinocytes bind IgG antibodies from the sera of LE patients with either monospecific anti-SSA/Ro, anti-RNP, or anti-Sm activity, which implies that these antigens have been made accessible on the cell surface by ultraviolet irradiation. Normal human sera or LE patient's sera with anti-double-stranded DNA, anti-single-stranded DNA, or antihistone activity do not bind to the surface of irradiated human keratinocytes. In control experiments, all antisera produced the expected patterns of nuclear and cytoplasmic staining of fixed permeabilized, unirradiated keratinocytes. Careful study of the viability and permeability of irradiated keratinocytes by several techniques showed that this apparent cell membrane expression of extractable nuclear antigens (SSA/Ro, RNP, and Sm) following irradiation was seen on injured keratinocytes whose cell membranes were intact, but not on dead cells. It is particularly significant that all six monospecific anti-SSA/Ro sera bound to irradiated keratinocytes, since this antibody antigen system is highly associated with photosensitive cutaneous LE.

Human keratinocytes synthesize, secrete, and deposit fibronectin in the pericellular matrix.

Fibronectin production by human keratinocytes cultured in serum-free, low-calcium medium without a fibroblast feeder layer was examined using several techniques. Immunohistochemical examination confirmed that the cultures were not contaminated with fibroblasts or Langerhans cells. By indirect immunofluorescence, fibronectin appeared as intracellular granules within all cells and as short radial fibrils between the cells and the substratum, and in the pericellular matrix. Conditioned media taken from 4-, 6-, 8-, 10-, and 12-day cultures contained fibronectin as measured by enzyme-linked immunosorbent assay in proportion to the cell number in cultures. Synthesis of fibronectin by 7-day keratinocyte cultures was determined by 18-h [35S]methionine metabolic labeling followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography. Fibronectin accounted for 12% of the secreted protein under these culture conditions. Our results indicate that human keratinocytes under conditions that prevent terminal differentiation in vitro can synthesize, secrete, and deposit fibronectin in the extracellular matrix.

The role of RNP, Sm, and SS-A/Ro-specific antisera from patients with lupus erythematosus in inducing antibody-dependent cellular cytotoxicity (ADCC) of targets coated with nonhistone nuclear antigens.

To better understand potential antibody-dependent mechanisms of tissue damage in lupus erythematosus (LE), an examination of whether antibodies to nonhistone nuclear antigens in LE patients' sera can induce ADCC of cellular targets coated with the corresponding antigens was undertaken. With high titer anti-RNP sera, significant ADCC was seen with monocyte (P less than 0.01), T-lymphocyte (P less than 0.001), and low-density lymphocyte (P less than 0.001) effectors. Using monocyte effectors, significant ADCC was seen with anti-RNP (P less than 0.01), anti-Sm (P less than 0.01), and anti-SSA/Ro (P less than 0.01), with the most profound lysis being with the anti-SSA/Ro sera. Neutrophils were ineffective in any nuclear antigen-antibody system tested. The effective mononuclear cell-mediated ADCC seen with anti-RNP, anti-Sm, and anti-SSA antisera may be related to the mononuclear cell-associated tissue change seen in cutaneous lupus lesions.

Mass filter and focusing ion detector for use with time-of-flight velocity distribution measurements.

A novel mass filter and focusing ion detector for time-of-flight studies of dissociative ionization fragments is described. The filter-dector combination is particularly suited for measuring the kinetic energy released in the molecular dissociation process. The mass filter utilizes a computer-controlled, time-dependent retarding potential synchronized with, and located a distance L from, a pulsed electron-bombardment ion source. Ions arriving at the filter at time t have a kinetic energy of mL(2)/2t(2). The retarding potential varies with time as mL(2)/2et(2), thus deflecting ions with masses less than m. Operation of the filter in a mode which provides unity mass resolution at 16 amu has been demonstrated. The detector consists of a channel electron multiplier and a focusing electrode configuration approximating that of a charged sphere above a grounded conducting plane. The planar input aperture of the detector is located just behind the mass filter along the ion flight path. The detector features high efficiency, large input aperture, low background, and simple operation. Ion transit times through the detector are small and essentially independent of the initial ion kinetic energy.

Mutual inductance bridge for low-temperature thermometry and susceptibility measurements.

We describe a solid-state mutual inductance bridge suitable for low-temperature thermometry and susceptibility measurements. The design features an electronically simulated variable mutual inductance. Particular care is taken to reduce spurious capacitive effects. The bridge is highly stable and linear. It has a resolution of 10(-4) over the range 15 microH to 150 mH, and a noise limited sensitivity of 55 I(p) (-1) nH with a l-s time constant, where I(p) is the rms primary current in mA. Application to thermometry is discussed.