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Biomedical subjects

T L Johnson

Publications and source records attributed to T L Johnson.

96 records · Page 6Linked to original sources
PubMedDate not supplied

Donath-Landsteiner hemolytic anemia due to an anti-Pr-like biphasic hemolysin.

Anemia, hyperbilirubinemia, and reticulocytosis subsequent to viral infection were present in a 32-year-old woman. The direct antiglobulin test was negative, and no unexpected antibodies were detected in pretransfusion tests. Rosettes of red cells (RBCs) around neutrophils were observed in peripheral blood smears, and a Donath-Landsteiner (D-L) test was positive. However, the patient did not show the classic features of paroxysmal cold hemoglobinuria (PCH). There was no hemoglobinuria, and in vivo hemolysis was not precipitated by cold. The D-L antibody was IgG, but classic anti-P specificity was not apparent. Rather, protease- or neuraminidase-treated RBCs, as well as certain sialic acid deficient RBCs of uncommon MN phenotypes, were not hemolyzed in D-L tests. Further, D-L antibody activity could be inhibited by MN sialoglycoprotein. These data support a diagnosis of chronic D-L hemolytic anemia, caused by an anti-Pr-like biphasic hemolysin.

Adult↗
PubMedDate not supplied

Differential effects of embryonic immobilization on the development of fibrocartilaginous skeletal elements.

The importance of mechanical influences during skeletal development has been well established in both experimental studies and computer models. Under conditions of embryonic immobilization, it has been observed that the early stages of joint formation proceed normally (up to and including interzone formation), but the later stages of joint cavitation and maintenance are impaired, resulting in fusion of the cartilaginous elements across the presumptive joint line. Two structures in particular are noticeably absent from late-stage synovial joints in immobilized chick embryos: the menisci of the tibiofemoral joint and the plantar tarsal sesamoid of the tibiotarsal joint. Both of these fibrocartilaginous structures are known to serve mechanical functions in postnatal animals, helping to distribute loads within the joint and, in the case of sesamoid structures, to provide a mechanical advantage to muscles acting across the joint. We demonstrate in this study that embryonic immobilization differentially affects the developmental fate of these two distinct fibrocartilages. The absence of the plantar tarsal sesamoid in late-stage immobilized embryos is due to a failure in the initial formation of this structure. In contrast, the early stages of meniscus formation proceed normally. Without the normal mechanical stimuli of skeletal muscle contractions, however, the meniscus fails to mature and ultimately degenerates.

Animals↗
PubMedDate not supplied

Cytologic features of ovarian tumors of low malignant potential in peritoneal fluids.

The distinction of ovarian tumors of low malignant potential (OTLMP) from invasive ovarian carcinomas has significant therapeutic and prognostic implications. This study was undertaken to define the cytologic features of OTLMP in peritoneal fluids and to compare them with the cytologic features of invasive carcinomas. Peritoneal fluids from 13 patients with OTLMP and 10 patients with invasive ovarian carcinoma contained neoplastic cells and were reviewed with attention to papillary fragment morphology, cellular pleomorphism and cytoplasmic and nuclear characteristics. Cytologic preparations from patients with OTLMP contained large, cohesive papillary fragments with smooth borders. The neoplastic cells were relatively small and uniform, with high nuclear-cytoplasmic (N/C) ratios (greater than 1:2), few intracytoplasmic vacuoles and inconspicuous nucleoli. Mitotic figures were rare. Peritoneal fluids from patients with invasive ovarian carcinoma contained smaller discohesive papillary fragments with irregular borders. The neoplastic cells were relatively large and pleomorphic, with low N/C ratios (less than or equal to 1:2), abundant intracytoplasmic vacuoles and prominent nucleoli; most preparations contained many single cells and mitotic figures.

Adult↗