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Biomedical subjects

R C Bahn

Publications and source records attributed to R C Bahn.

At least 37 records · Page 2Linked to original sources
PubMed1982

Toxic shock syndrome. A fatal case with autopsy findings.

Although the clinical and laboratory features of the toxic shock syndrome have recently been further defined, the pathologic lesions attending this disorder are as yet primarily unstudied. We present the autopsy findings in a fatal case of toxic shock syndrome, which occurred in a 17-year-old girl. These observations are used as a focus for the discussion of possible pathophysiologic mechanisms operative in this disease and are contrasted with autopsy findings in several other pathologic entities that are often confused with toxic shock syndrome.

Adolescent↗
PubMed1982

Computed transmission ultrasound tomography.

Beginning with the wave equation, we have derived the classic reconstruction equations, which assume the ultrasonic energy travels in a straight line. The straight line reconstruction methods result in images that are not absolutely quantitative, although they may be useful in delineating speed and attenuation within two-dimensional cross sections, especially in organs such as the breast. Aberrations associated with straight-line reconstruction images are results of the effects of refraction and of diffraction. In addition, these methods assume that the acoustic wave travels within a plane and not in three dimensions; thus the assumed dimensionality of the problem also gives aberrations in the final image. The effects of diffraction are very complex and, given the current methods of measuring arrival time and amplitude, cause aberrations in the image, which result in errors both in geometry and in magnitude of the reconstructed values. Correction of diffraction effects with techniques termed 'diffraction tomography' are being investigated and have resulted in some preliminary data.

Breast Neoplasms↗
PubMed1981

Further characterization of lymphocytes from human colonic lamina propria: identification of TG cells.

For the first time, TG cells have been identified in human colon using EDTA-collagenase-prepared, macrophage-depleted isolates of lamina proprial lymphocytes (LPL). Specimens of human colon were obtained from patients undergoing surgery for idiopathic inflammatory bowel disease (IBD), colorectal cancer (Dukes' B or C), other colonic inflammations or benign polyps. Of additional interest were quantitative findings which showed lower TG values in LPL from patients with IBD, regardless of disease activity or steroid therapy, and in Dukes' Group C cancers, compared to the other groups. However, these differences of TG values were not reflected in the peripheral blood lymphocytes (PBL) in which, compared to healthy controls, the numbers of circulating TG cells were greater in patients with Dukes' B or C cancers and in those with moderately or severely active IBD receiving steroids. These quantitative differences re-emphasize the need for concurrent observations on PBL and LPL in these diseases, particularly in experiments to determine the functional properties of their TG subsets, including mediation of natural killing, antibody-dependent cellular cytotoxicity and their immunoregulatory properties. The identification of TG cells per se in colonic LPL provides a basis for such studies.

Adolescent↗
PubMed1979

Emission-computed tomography and its application to imaging of acute myocardial infarction in intact dogs using Tc-99m pyrophosphate.

The techniques of emission-computed tomography have been used to obtain in vivo quantitative estimates of the three-dimensional distribution of gamma-emitting radionuclides in dog hearts. Conjugate views, obtained for 60 equiangular projections around 360 degrees by rotating the object in front of a gamma camera, were used to reconstruct multiple-level emission transaxial images for various test objects, and for dogs with surgically induced acute myocardial infarcts. Corrections for attenuation were performed in the backprojection step of the convolution algorithm used for reconstruction. Quantitative estimates of the spatial extent and concentration of activity were obtained to within 10--15% rms error. Correlations were obtained between the radionuclide and histopathologic estimates of the extent and location of infarction.

Animals↗