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R C Chase

Publications and source records attributed to R C Chase.

2 recordsLinked to original sources

Frequency and significance of immunoglobulin M antibody to hepatitis B core antigen in corticosteroid-treated severe chronic active hepatitis B.

To assess the frequency and significance of immunoglobulin M (IgM) antibody to hepatitis B core antigen (anti-HBc) in corticosteroid-treated severe chronic active hepatitis B, we tested 96 serum samples from 16 patients who were seropositive for hepatitis B surface antigen (HBsAg) (group 1) and 8 HBsAg-negative, anti-HBc-positive patients (group 2) by enzyme-linked immunoassay. Samples obtained in the presence and absence of disease activity before, during, and after long-term corticosteroid therapy (mean duration, 42 +/- 7 months) were evaluated. Seropositivity for IgM antibody was demonstrated in 12 group 1 patients, including 9 tested before corticosteroid therapy; no group 2 patients were seropositive. Seropositivity was more common in serum samples obtained during active than during inactive disease (51% versus 22%; P less than 0.05) and more frequent in serum samples that contained hepatitis B e antigen (46% versus 11%; P less than 0.02) and hepatitis B virus deoxyribonucleic acid (50% versus 24%; P less than 0.05) than in those without these markers. In some patients, seropositivity persisted or recurred intermittently during corticosteroid therapy for up to 57 months. We conclude that seropositivity for IgM antibody can be demonstrated frequently by enzyme-linked immunoassay in corticosteroid-treated patients with severe disease. Seropositivity reflects active virus replication, and it is commonly associated with inflammatory activity. The duration of seropositivity may be protracted during long-term corticosteroid therapy.

Adrenal Cortex Hormones

An improved image algorithm for CT scanners.

A common artifact in CT head-section images is a cupping or broad "whitening" effect near the skull which is due at least in part to the polychromaticity of the x-ray beam. In this paper, a general method is presented for removing this artifact empirically by a combination of two approaches. The gross cupping is removed by modifying the raw transmission data prior to reconstruction. The residual whitening near the bone is removed conveniently by modifying the reconstruction filter function. Examples of the modifications are shown using the AS&E CT scanner. The method convolves or deconvolves the CT image with an appropriate point spread function. Since the filter-function modifications are done conceptually in real space rather than in frequency space, the details of the modifications are more easily understood.

Head