Focal nodular hyperplasia and hepatic adenoma: comparison of angiography, CT, US, and scintigraphy

The authors reviewed 23 cases of focal nodular hyperplasia and 13 cases of hepatic adenoma, all of which were confirmed pathologically. All solitary masses that exhibited normal or increased uptake of technetium 99m-sulfur colloid were shown to be hyperplasia; while previous criteria such as a central blood supply on angiograms or a central scar on computed tomography (CT) or ultrasound (US) scans were helpful, they were relatively infrequent. A mass that was slightly hypodense and homogeneous on a CT or US scan and highly vascular with an intense capillary stain on an angiogram was almost always hyperplasia. Acute hemorrhage within a focal hepatic tumor was common in adenoma but did not occur in hyperplasia.     

Splenic primitive hematopoietic stem cell (PHSC) activity is enhanced by steel factor because of PHSC proliferation

To test whether primitive hematopoietic stem cells (PHSCs) are stimulated by Steel (SI) factor (c-kit ligand) in vivo, donor mice were studied after three or seven daily injections of SI factor. PHSC activity was measured as long-term erythroid and lymphoid competitive repopulating ability. Cells to be tested (usually marrow or spleen cells from treated donors) were mixed with untreated competitor marrow that produces erythrocytes and lymphocytes that are genetically distinguishable from the donors by differences in hemoglobin (Hb) and glucosephosphate isomerase (GPI) markers. These cell mixtures were injected into lethally irradiated hosts, and after 111 to 293 days, functional abilities of donor PHSC populations were assessed and expressed as percentages of donor-type Hb and GPI in the host's circulating erythrocytes and lymphocytes, respectively. A striking increase in splenic PHSC activity occurred after seven daily injections of SI factor, with a much smaller increase after three daily injections. Both three and seven daily injections of SI factor slightly reduced marrow PHSC activity. Rapid cycling greatly increases PHSC vulnerability to 5-fluorouracil (5FU). To test whether SI factor stimulates PHSCs into rapid cycling, donor mice were given a dose of 5FU in addition to SI factor. The increase in splenic PHSCs after 7 days of treatment with SI factor occurred to a similar degree whether donors were or were not treated with 5FU on day 8. However, a dose of 5FU on day 4 of the SI factor treatments almost totally prevented the increase in splenic PHSC activity. Apparently this increased activity requires PHSC cycling throughout the period of SI factor treatment.     

Cerebellopontine angle-petromastoid mass lesions: comparative study of diagnosis with MR imaging and CT

Capabilities of computed tomography (CT) and magnetic resonance (MR) imaging in the diagnosis of cerebellopontine angle-petromastoid (CPA-PM) lesions were compared in 75 patients. CT and MR demonstrated 95.8% and 98.7% of the lesions, respectively. MR was often more helpful for characterization of neuromas, epidermoid cysts, exophytic gliomas, and vascular lesions, while CT was usually more informative for meningiomas, metastases, and tympanomastoid cholesteatomas. A specific diagnosis could be made with MR for most types of lesions through use of relaxation parameters and characteristic morphologic changes. Size, shape, location, and contour of the lesions, however, were generally more helpful for differential diagnosis than relaxation times. With the exception of metastatic lesions, cholesteatomas, and some meningiomas, MR was usually more helpful than CT in defining the full extent of the lesions and their relationships to contiguous structures. MR, because of its high accuracy in lesion detection, characterization, and localization, is a suitable primary diagnostic modality for evaluating patients with suspected CPA-PM lesions.     

Selective uptake of [3H]arachidonic acid into the dense tubular system of human platelets

We have used quantitative electron microscopic autoradiography to characterize the subcellular distribution of arachidonoyl phospholipids following brief (5 minutes) exposure of unstimulated human platelets to [3H]arachidonic acid. Labeled arachidonate was taken up rapidly and incorporated into phospholipids. Phospholipid radioactivity was preserved and spatially fixed during tissue processing for electron microscopy. Analysis of autoradiographs showed that following a brief exposure to 750 nmol/L [3H]arachidonate, there is selective labeling of an internal membrane compartment composed of the dense tubular system and the open canalicular system. The plasma membrane, platelet granules, and nonmembranous cytoplasm were not labeled. Since the open canalicular system is continuous with the plasma membrane and since phospholipids in continuous membranes are freely diffusible, our observations indicate that [3H]arachidonate was incorporated into phospholipids within the dense tubular system and not the open canalicular system. Thus, the dense tubular system, known to contain cyclooxygenase activity, incorporates arachidonate selectively following brief exposure to this fatty acid, presumably to concentrate it in proximity to enzymes for icosanoid synthesis.     

Rga (Rodgers) and the HLA Region: Linkage and Associations

In 19 families with 97 children the segregation of Rg^a (Rodgers) was found to be compatible with Mendelian inheritance and five backcross and 14 intercross families were found among HLA and Bf typed families. Close linkage (lods + 17.82) without recombination was found between Rg and the HLA region, with a direct count of 96 nonrecombinant meioses for Rg-HLA-B. Kg- was strongly associated with HLA-B8 (29 of 30 haplotypes) and probably associated with Bw40, but did occur on other HLA-B haplotypes. By inference.Rg^- is negatively associated with Ch^- (Chido). The Rg^-Ch^- haplotype has not been observed. Rg³ and Ch^a may or may not be coded for by different sites of the same cistron closely linked to HLA-B:C and cannot as yet be excluded from being parts of B or C.