Polymorphonuclear leukocyte heterogeneity in neonates and adults

We have used a mouse monoclonal antibody (31D8) to determine whether differences in neutrophil (PMN) subpopulations might help explain decreased PMN chemotaxis in neonates compared with that of adults. 31D8 has been shown to bind heterogeneously to adult PMNs. Approximately 80% of the PMNs that strongly bind 31D8 (31D8 "bright") are the same cells that depolarize and migrate chemotactically when stimulated with the chemoattractant N-formyl-methionylleucylphenylalanine, while the 20% that weakly bind 31D8 fail to similarly respond. All neonatal PMNs bound 31D8 heterogeneously. There was a smaller population of 31D8 "bright" cells in neonates at birth (76% +/- 6%, n = 45) compared with that of neonates at three to 15 days of age (82% +/- 5%, n = 10, P less than 0.002) and both were smaller than that of adults (88% +/- 4%, n = 45, P less than 0.001 and P less than 0.001). Neonatal cord PMNs, which traversed a micropore filter in a modified Boyden chemotaxis chamber in the presence of a chemoattractant, had an increased percentage of 31D8 "bright" cells (89% +/- 7%) than did PMNs which remained above the filter (82% +/- 7%, n = 10, P = 0.034). PMN chemotaxis was less in neonates at birth (32.7 +/- 4.5 micron) than at three to six days of age (36.8 +/- 11.3 micron) and both were decreased compared with that of adults (69.1 +/- 12.4 micron, P less than 0.001 and P less than 0.001). These findings indicate that decreased PMN chemotaxis in neonates may be due in part to a smaller PMN subpopulation of highly motile cells.     

Human marrow erythropoiesis in culture. I. Characterization of methylcellulose colony assay

We examined the morphological and functional characteristics of human marrow erythrocytes cultured with a recently developed methylcellulose colony assay technique. Erythrocytic cells in various stages of development were observed, and a significant degree of maturational synchrony within individual colonies was noted. By light microscopy, colonies consisting of late normoblasts appeared compact, had an orange hue attributable to their hemoglobin, and demonstrated pseudoperoxidase activity, whereas colonies composed of early erythroblasts grew less compact or in clusters of smaller cell aggregates and showed no reddish tinge. Colonies possessing intermediate features were also observed. Maturational synchrony of individual colonies was confirmed using ransmission and scanning electron microscopy. The ultrastructure and cytochemistry of most immature cells were normal. The mature erythrocytes, however, were severely microcytic and hypochromic and contained one to several Heinz bodies. These defects in the cytoplasmic maturation of erythrocytes corresponded with impaired granulocytic maturation in culture, which we observed previously, and suggest environmental or nutritional defects in culture. Linearity of the method was confirmed using five normal bone marrows. Erythropoietin dose-responses observed in ten normal marrows were comparable to the previously reported results and revealed significant variation in individual plating efficiencies.     

Myeloid but not lymphoid cells carry the 5q deletion: polymerase chain reaction analysis of loss of heterozygosity using mini-repeat sequences on highly purified cell fractions

Interstitial deletions of the long arm of chromosome 5 are among the most characteristic abnormalities observed in myeloid disorders. To assess the lineage involvement of peripheral blood cells from patients with a 5q--anomaly, purified neutrophils, monocytes, T lymphocytes, and B lymphocytes were analyzed for loss of heterozygosity using six different highly polymorphic mininucleotide and dinucleotide (CA) repeat sequences from the 5q31 to 5q33 region. Ten patients were screened by polymerase chain reaction (PCR) amplification and proved to be informative for at least one marker. Six patients showed a complete or partial disappearance of an allele in myeloid cells, whereas cells of lymphoid lineages exhibited full heterozygosity. The other patients displayed no allelic loss, indicating that the informative markers were located outside the deleted chromosomal segments. In addition, three female patients who were also polymorphic for the BstXI site in the PGK- 1 gene were analyzed for the methylation status of this gene. Clonality of hematopoiesis, as determined by non-random X-chromosome inactivation, followed the same cell pattern as the 5q-specific allelic losses. In conclusion, using tumor-specific and clonal markers, we have demonstrated that the 5q- anomaly is restricted to cells of myeloid origin, leaving lymphoid cells unaffected.     

Enhanced engraftment of hematopoietic progenitor cells in mice treated with granulocyte colony-stimulating factor before low-dose irradiation: implications for gene therapy

Gene therapy for inherited disorders of blood cells will require both efficient methods for stable gene transfer and nonablative bone marrow conditioning regimens to allow engraftment of modified hematopoietic progenitor cells (HPCs). We have used a sensitive murine system for detecting HPC engraftment using congenic C57BL/6 mice that differ at the Ly5 locus, which encodes the leukocyte common antigen. The system relies on the ability of monoclonal antibodies with specificity for Ly5.1 and Ly5.2 (revised nomenclature: CD45.1 and CD45.2, respectively) to distinguish donor and recipient peripheral blood leukocytes after transplantation of purified Sca-1+ bone marrow-derived HPCs. No detectable engraftment occurred in nonirradiated recipient mice, even when as many as 2.0 x 10(6) SCa-1+HPCs were transplanted. However, in mice receiving total body irradiation (TBI), engraftment increased as a function of pretransplantation radiation dose, number of transplanted cells, and time after transplantation. Moreover, mice receiving either granulocyte colony-stimulating factor (G-CSF) or G-CSF+ stem cell factor before low-dose TBI (160 cGy) exhibited a marked increase in engraftment compared with mice receiving a vehicle control before low- dose TBI (18.9% and 20.6% v 5.6% at a 1 month, respectively; 29% and 35% v 15.1% at 4 months, respectively). Use of growth factor pretreatment even allowed TBI doses as low as 30, 70, or 120 cGy to achieve significant engraftment of donor progenitors (0.3%, 1.5%, and 6.8% at 1 month, respectively; 1.7%, 5.8%, and 13.9% at 4 months, respectively). All animals remained healthy during the observation periods. Thus, growth factor preconditioning of the recipient followed by low-dose TBI may provide an optimal balance between safety and efficacy in achieving required levels of engraftment for gene therapy of blood disorders.     

Differentiation of pulmonary parenchymal consolidation from pleural disease using the sonographic fluid bronchogram

The nature of pleural-based thoracic collections may be sonographically confusing. To help lessen this confusion, the fluid bronchogram, a useful sonographic sign of pulmonary parenchymal consolidation, is described. Bronchi containing fluid in consolidated lung can be identified using ultrasound.     

Modulation of responses to optic flow in area 7a by retinotopic and oculomotor cues in monkey

Perception of two- and three-dimensional optic flow critically depends upon extrastriate cortices that are part of the 'dorsal stream' for visual processing. Neurons in area 7a, a sub-region of the posterior parietal cortex, have a dual sensitivity to visual input and to eye position. The sensitivity and selectivity of area 7a neurons to three sensory cues - optic flow, retinotopic stimulus position and eye position - were studied. The visual response to optic flow was modulated by the retinotopic stimulus position and by the eye position in the orbit. The position dependence of the retinal and eye position modulation (i.e. gain field) were quantified by a quadratic regression model that allowed for linear or peaked receptive fields. A local maximum (or minimum) in both the retinotopic fields and the gain fields was observed, suggesting that these sensory qualities are not necessarily linearly represented in area 7a. Neurons were also found that simply encoded the eye position in the absence of optic flow. The spatial tuning for the eye position signals upon stationary stimuli and optic flow was not the same, suggesting multiple anatomical sources of the signals. These neurons can provide a substrate for spatial representation while primates move in the environment.      

Synthetic or natural surfactants

Surfactant replacement therapy is one of the most studied interventions in neonatal medicine, with many thousands of infants having been enrolled in randomized clinical trials. It is clear that surfactant therapy reduces neonatal mortality and the risk of pulmonary air leaks in babies with or at risk of developing respiratory distress syndrome. Yet some doubts linger over other aspects of this therapy, despite it having been an acceptable and proven therapy for the past 7–10 years. As regards timing of treatment, the earlier the better, with true prophylaxis being reserved for babies of less than 28 weeks' gestation. Natural surfactant preparations containing surfactant proteins B and C act more rapidly than their synthetic protein-free counterparts and probably also have a greater impact on reducing neonatal mortality and pulmonary air leaks. Fears raised about immunological effects, prion transmission and chemical contamination of natural surfactants have not been substantiated. Long-term follow-up studies do not show any differences in outcome between treated and non-treated infants, except that the incidence and severity of retinopathy of prematurity might be reduced by treatment with natural surfactant. Further research is needed and this will include more detailed follow-up studies, newer indications for surfactant therapy and the testing of newer preparations with synthetic peptides or protein analogues added.     

Orthotopic cardiac transplantation: evaluation with CT

As cardiac transplantation has become widely available, computed tomography (CT) of the chest has played a useful role in the examination of patients after heart transplantation. To determine anatomic features related to the procedure, the authors evaluated 59 scans in 46 patients who had undergone orthotopic cardiac transplantation. Aortic anastomosis (seen in 98% of scans) and altered spacing between the great vessels (83%) proved to be the most common and most reliable findings. Other features including atrial anastomosis, high main pulmonary artery segment, remnant superior vena cava, and cardiac reorientation were also seen. Accurate interpretation of adenopathy, mediastinal abscess, and pericardial effusion will be enhanced in these patients through a better understanding of the cardiovascular-pericardial complex, which is afforded by CT.