The endogenous lectin of human platelets is an alpha-granule component

Platelets from patients with several bleeding disorders (congenital afibrinogenemia, Glanzmann's thrombasthenia, gray platelet syndrome, and Hermansky-Pudlak syndrome) were evaluated for both platelet-bound and platelet-free hemagglutination activities. Thrombin and A23187 activated afibrinogenemic, Hermansky-Pudlak, and thrombasthenic platelets had normal platelet-bound hemagglutination activity. Gray platelets activated by the same agents had deficient platelet-bound hemagglutination activity. In contrast, thrombin-activated afibrinogenemic, gray, and thrombasthenic platelets lacked platelet- free hemagglutination activity. Only thrombin-activated Hermansky- Pudlak platelets had a normal level of platelet-free hemagglutination activity. On the basis of these results and the distinguishing characteristics of the defective platelets, it is concluded that the alpha-granules are the origin of the enhanced hemagglutination activity. Furthermore, it is suggested that the insufficiency of the platelet-bound agglutinin may be the cause of the inability of gray platelets to aggregate normally in response to thrombin.     

Breast skin calcifications: localization with a stereotactic device

Calcifications that lie within the skin of the breast may be mistakenly thought to be intraparenchymal on mammograms if they are projected over breast tissue in two views. A simple, reliable technique was developed to determine calcification location. It uses a commercially available stereotactic localization device and has been used successfully in six patients.     

An epidemiologic case-control study of central nervous system tumors in children and parental occupational exposures

A population-based case-control study was conducted with 338 patients less than 15 years of age who were diagnosed with a primary tumor of the central nervous system from January 1968 through December 1977 in 53 contiguous New York counties. The study also included 676 controls who were selected from the birth certificate files of the New York State Department of Health. Parental occupational exposures at the time of each child's birth and at the time of tumor diagnosis were derived from maternal interviews. The current data set failed to show any consistent association between childhood central nervous system tumor risk and paternal occupational exposures to hydrocarbons or to electromagnetic fields, or employment in the aerospace industry or pulp and paper manufacturing. Findings for occupational exposures to ionizing radiation were also inconsistent. A positive association was observed between central nervous system tumor risk and paternal exposures to ionizing radiation based on industrial codes. Odds ratios ranged from 1.71 to 2.15. This association was not observed when paternal occupational titles were used to define exposure (range of odds ratios, 1.01-1.10). Maternal exposures to ionizing radiation were not related to risk regardless of the classification scheme used.     

Fixed spinal cord: diagnosis with MR imaging

Pulsatile motion of the spinal cord was examined with phase imaging techniques. Sagittal images of the spinal cord were obtained at different times of the cardiac cycle in healthy volunteers, as well as in patients in whom the spinal cord either was tethered, was compressed, or contained an intramedullary lesion. Pulsatile velocity changes of the spinal cord, observed on the phase images, were most marked at the cervical-upper thoracic level. Cord motion was found to be significantly decreased in cases in which the cord was either tethered or compressed. Cord enlargement due to an intramedullary lesion generally did not lead to decreased cord motion. Imaging of pulsatile cord motion may be clinically useful in evaluating diseases restricting cord motion or changing the status of parenchymal compliance.     

An investigation of the neuroprotective effects of tetracycline derivatives in experimental models of retinal cell death

The purpose of this study was to determine the efficacy and putative mechanisms of action of tetracycline and minocycline in inhibiting retinal cell apoptosis after glutamate-induced excitotoxicity and trophic factor deprivation in a retinal cell line (E1A-NR.3) and in primary mixed retinal cell cultures. In addition, a differentiated PC-12 cell line was used to determine whether minocycline was neuroprotective after trophic withdrawal in a pure neuronal cell line devoid of glia. Results from this study demonstrated that minocycline, but not tetracycline, is protective in in vitro models of excitotoxicity-induced retinal cell apoptosis. Moreover, the protective effects provided by minocycline in retinal cells seemed independent of actions on N-methyl-D-aspartate receptors (NMDARs) and glutamate receptor-mediated Ca(2+) influx. Doses of the NMDAR antagonist MK-801 (dizocilpine) and minocycline that alone provided no significant neuroprotection resulted in enhanced retinal cell survival when applied concurrently, suggestive of distinct signaling pathways, and minocycline was without effect on glutamate-induced Ca(2+) influx, as assessed by calcium imaging. Minocycline was also neuroprotective after trophic factor withdrawal, producing a decrease in apoptosis and caspase-3 activation in both retinal cells and the PC-12 neuronal-like cell line. These results support a role for minocycline as a retinal neuroprotectant and demonstrate that the antiapoptotic actions of minocycline in retinal cells do not arise from the blockage of NMDARs or glutamate receptor-mediated Ca(2+) influx but do involve inhibition of caspase-3 activation. In addition, the survival-promoting actions of minocycline may arise via actions on both neuronal and non-neuronal cell targets.     

The role of personal contact with HIV-infected people in explaining urban,African American preadolescents' attitudes toward peers with HIV/AIDS

This article presents the results of a study aimed at describing African American youths' attitudes toward peers with HIV/AIDS and identifying correlates of these attitudes based on the contact theory. Baseline data from a sample of African American, urban mothers and their youth (n = 197) participating in a family-based HIV prevention program were analyzed. In support of contact theory, preadolescents' close relationship to persons infected with HIV/AIDS was highly related to their attitudes. However, no relationship was found between maternal attitudes or communication variables and youth attitudes. The implications of youths' experience with persons with HIV/AIDS as part of prevention programming are discussed.     

Different chromogranin immunoreactivity between prion and a-beta amyloid plaque

Brain lesions in Creutzfeldt-Jakob disease (CJD) include spongiform change, neuronal loss, amyloid plaques, astrogliosis and microglial activation. Microglia are thought to play a key role in prion-induced neurodegeneration. However, the intermediate molecules supporting relationships between neurons and microglia are still unknown. Chromogranins (Cg) are soluble glycophosphoproteins that can activate microglial cells leading to a neurotoxic phenotype. The immunoreactive patterns of CgA and CgB were investigated in CJD and compared to those observed in Alzheimer's disease. We found that CgB, but not CgA, immunoreactivity was selectively associated with prion protein deposits, whereas CgA was only seen in Abeta plaques. This suggests a specific influence of the constitutive amyloid protein on chromogranin secretion and a role of CgB in the CJD neurodegenerative process.