Context-dependent memory under stressful conditions: the case of skydiving.

Two experiments examined the effect of differing levels of emotional arousal on learning and memory for words in matching and mismatching contexts. In Experiment 1, experienced skydivers learned words either in the air or on the ground and recalled them in the same context or in the other context. Experiment 2 replicated the stimuli and design of the first experiment except that participants were shown a skydiving video in lieu of skydiving. Recall was poor in air-learning conditions with actual skydiving, but when lists were learned on land, recall was higher in the matching context than in the mismatching context. In the skydiving video experiment, recall was higher in matching learn-recall contexts regardless of the situation in which learning occurred. We propose that under extremely emotionally arousing circumstances, environmental and/or mood cues are unlikely to become encoded or linked to newly acquired information and thus cannot serve as cues to retrieval. Results can be applied to understanding variations in context-dependent memory in occupations (e.g., police, military special operations, and Special Weapons and Tactics teams) in which the worker experiences considerable emotional stress while learning or recalling new information.

Reconstitution in severe combined immunodeficiency by transplantation of marrow from an unrelated donor.

A patient with severe combined immunodeficiency received seven transplants of bone marrow from an HLA-B-compatible and HLA-D-compatible unrelated donor in an attempt to provide immunologic reconstitution. The first four transplants achieved restricted engraftment with evidence of rudimentary immunologic function. A fifth transplant, given after low-dose cyclophosphamide, produced reconstituion of cell-mediated immunity. Marrow aplasia developed after recontamination with a nonpathogenic microflora. Transplantation of marrow previously stored in liquid nitrogen was ineffective. A subsequent transplant, administered after high-dose cyclophosphamide, achieved durable engraftment, with complete hematopoietic and immunologic reconstitution. Seventeen months after transplantation, full functional engraftment persists. Graft-versus-host disease has been chronic and moderately severe, but limited to the skin and oral mucosa. Transplantation of marrow from unrelated histocompatible donors may provide a useful treatment for patients with severe combined immunodeficiency or aplastic anemia who lack a matched sibling or related donor.

Congenital neutropenia: an intrinsic cell defect demonstrated by electron microscopy of soft agar colonies.

Congenital neutropenia (CN), a disease characterized by recurrent infections leading to death in infancy, shows a maturation arrest of the myeloid series at the promyelocyte-myelocyte level. The potential value of marrow transplantation in this disease would be determined by the nature of the underlying defect. However, studies to date have failed to define whether the defect is intrinsic in the cells or attributable to "environmental" factors. Therefore, marrow of four patients with CN was cultured on soft agar, and the colonies were analyzed by a newly developed ultrastructural method. In parallel, patients' cells were used in feeder layers for normal marrow. Although the patients' colonies appeared grossly normal in size and number, electron microscopy showed only rare neutrophil colonies. These colonies contained markedly aberrant cells exhibiting asynchronous nucleocytoplasmic maturation, convoluted nuclei, excessive cytoplasm, and dearth of granules. Monocyte and eosinophil colonies differentiated normally. Patients' cells and sera supported growth of normal colonies. The studies have demonstrated unequivocally that the neutrophil cell line of patients with CN is intrinsically defective and suggest that attempts at marrow grafting are warranted.

Chronic mucocutaneous candidiasis with macrophage dysfunction, a plasma inhibitor, and co-existent aplastic anemia.

A 56-year-old man developed chronic mucocutaneous candidiasis (MCC) and pernicious anemia. Nine years later he developed aplastic anemia which ultimately was fatal. A small thymoma was found at autopsy. He was anergic and his mononuclear leukocytes (MNL) failed to undergo a proliferative response in culture to soluble antigens. His monocytes did not mediate a proliferative response by lymphocytes from sensitized control donors when stimulated with Monilia albicans antigen but did mediate a mixed leukocyte reaction normally. His plasma contained a poten inhibitor of -3H-thymidine incorporation by sensitized control MNL when stimulated with soluble antigens but was not inhibitory of the mixed leukocyte reaction, lymphoproliferative responses to plant mitogens, and was not shown either in vivo or in vitro to depress hematopoiesis. Patient lymphocytes were responsive to plant mitogens, Monilia antigen, in the mixed leukocyte reaction, and produced macrophage migration inhibitory factor in response to Monilia antigen. After plasmapheresis, delayed hypersensitivity and lymphoproliferative responses to soluble antigens were temporarily restored. This case implicates the macrophage in the pathogenesis of MCC and demonstrates some consequences of chronic monocyte dysfunction. The inhibitor of some expressions of cell-mediated immunity was removed by plasmapheresis.

In vitro differentiation of human marrow cells into T lymphocytes by thymic extracts using the rosette technique.

The manner by which human and calf thymic extracts induce precursor cells of human marrow to differentiate in vitro into T lymphocytes has been studied using as a T-cell marker the spontaneous rosette formation technique of human T lymphocytes with sheep erythrocytes (E rosette). These findings confirm previous observations made in the study of the same process using a different T-cell marker, specific antigenicity recognizable by a heterologous anti-human T-cell serum in a microcytotoxicity test. The number of cells revealing evidence of differentiation demonstrated by the E rosette formation technique is smaller than that obtained with the anti-human T-cell serum, indicating perhaps that a different stage of maturation of T lymphocytes is recognized by the antiserum from the one detected by spontaneous rosette formation. Based on the effects of specific inhibitors of nucleic acids and protein synthesis, it can be concluded that these thymic extracts ultimately act by influences exerted in the cell nucleus and that RNA and protein synthesis are required for the differentiation of precursor cells into T lymphocytes induced by thymic extracts. In addition, continued protein synthesis appears to be required for maintenance of receptors for sheep erythrocytes on the cell surface.

Congenital neutropenia: impaired maturation with diminished stem-cell input.

Children with congenital neutropenia (Kostman disease) present a syndrome of recurrent and eventually fatal bacterial infections. The disease is uniformly lethal and the mean age at death is 24 months. To attempt to better understand the nature of this inborn error, we have studied marrow and peripheral blood of 3 children with the disease. Along with classic morphologic analysis we have used the technic of soft agar bone marrow culture in vitro. All 3 patients showed marked deficiency of numbers of neutrophils in the peripheral blood, intermittent monocytosis especially with infection, and predominant nitroblue tetrazolium (NBT) dye staining in monocytes during infection. The marrow of all 3 patients showed evidence of maturation arrest at the promyelocyte stage and very few or no neutrophils. Two cases showed no neutrophils in the Rebuck skin window inflammatory study. The 3rd case, however, developed small numbers of neutrophils in the peripheral blood, up to 6%, but the first 2 patients, although studied on many occasions, did not show neutrophils above 1%. Evidence from soft agar culture of bone marrow in 1 patient was compatible with the view that development of committed neutrophil stem cells is defective. This patient did not develop neutrophils in soft agar culture and showed loose colonies developing only to promyelocytes. In the 2nd case, where depression of neutrophil development was somewhat less severe clinically, culture of the marrow in soft agar yielded normal neutrophil colonies and none of the loose colonies showing arrested maturation were seen. These findings suggest that the basic mechanism underlying the congenital neutropenias may differ from patient to patient.

Granulocyte colonies derived from lymphocyte fractions of normal human peripheral blood.

Granulocyte colonies can be grown from leukocyte-rich plasma obtained from normal human peripheral blood. Purification of lymphocytes by the Ficoll-Hypaque gradient method and subsequent removal of monocytes achieved a 10-fold increase in the number of colonies formed, suggesting that the colony-forming cell is nonadherent, nonphagocytic, and morphologically difficult to distinguish from a lymphocyte. Ultrastructural analysis of intact colonies by a new method developed for this purpose showed orderly differentiation and maturation. Only undifferentiated cells were seen in colonies on day 5, promyelocytes with developing primary lysosomes were present on day 9, whereas myelocytes and metamyelocytes were most prevalent on days 15 and 21, respectively. The studies suggest where further concentration of precursor cells may be attempted, and where further functional and histochemical analysis of colonies on the ultrastructural level will be possible.

Congenital neutropenia: in vitro growth of colonies mimicking the disease.

Congenital neutropenia is a lethal disease characterized by recurrent infections beginning in the neonatal period, absence of neutrophils in the peripheral blood, eosinophilia, and monocytosis. The bone marrow shows an apparent "maturation arrest" of the neutrophil series at the promyelocyte stage. Granulocytic colonies grown in vitro in soft agar medium show normal development of eosinophilic colonies and monocyte-macrophage colonies, but defective neutrophil maturation. The abnormal colonies observed contained only myeloblasts and promyelocytes. Thus, it seems to have been possible to mimic in vitro the abnormal differentiation that is observed in vivo.