Ex vivo expansion of genetically marked rhesus peripheral blood progenitor cells results in diminished long-term repopulating ability

The possibility of primitive hematopoietic cell ex vivo expansion is of interest for both gene therapy and transplantation applications. The engraftment of autologous rhesus peripheral blood (PB) progenitors expanded 10 to 14 days were tracked in vivo using genetic marking. Stem cell factor (SCF)/granulocyte colony-stimulating factor (G-CSF)-mobilized and CD34-enriched PB cells were divided into two equal aliquots and transduced with one of two retroviral vectors carrying the neomycin-resistance gene (neo) for 4 days in the presence of interleukin-3 (IL-3), IL-6, and SCF in the first 5 animals, IL-3/IL-6/SCF/Flt-3 ligand (FLT) in 2 subsequent animals, or IL-3/IL-6/SCF/FLT plus an autologous stromal monolayer (STR) in the final 2. At the end of transduction period, one aliquot (nonexpanded) from each animal was frozen, whereas the other was expanded under the same conditions but without vector for a total of 14 days before freezing. After total body irradiation, both the nonexpanded and expanded transduced cells were reinfused. Despite 5- to 13-fold higher cell and colony-forming unit (CFU) doses from the expanded fraction of marked cells, there was greater short- and long-term marking from the nonexpanded cells in all animals. In animals receiving cells transduced and expanded in the presence of IL-3/IL-6/SCF/FLT, engraftment by the marked expanded cells was further diminished. This discrepancy was even more pronounced in the animals who received cells transduced and expanded in the presence of FLT and autologous stroma, with no marking detectable from the expanded cells. Despite lack of evidence for expansion of engrafting cells, we found that the addition of FLT and especially STR during the initial brief transduction period increased engraftment with marked cells into a clinically relevant range. Levels of marked progeny cells originating from the nonexpanded aliqouts were significantly higher than that seen in previous 4 animals receiving cells transduced in the presence of IL-3/IL-6/SCF, with levels of 10% to 20% confirmed by Southern blotting from the nonexpanded IL-3/IL-6/SCF/FLT/STR graft compared with 0.01% in the original IL-3/IL-6/SCF cohort. These results suggest that, although expansion of PB progenitors is feasible ex vivo, their contribution towards both short- and long-term engraftment is markedly impaired. However, a brief transduction in the presence of specific cytokines and stromal support allows engraftment with an encouraging number of retrovirally modified cells.     

Target-promoted alkylation of DNA

For 13 years between 1980 and 1992, 23 patients needed pacemaker (PM) implantation because of bradyarrhythmia, 21 of atrial fibrillation and two of complete A-V block, after valve surgery. Five of 88 survivors (5.7%) after OMC, 11 of 227 (4.8%) after MVR, one of 169 (0.6%) after AVR, five of 67 (7.4%) after MVR + AVR and one of 15 (6.7%) after TVR underwent PM implantation in postoperative period. Two cases who had heart failure was implanted PM in early postoperative period. In late period, the mean duration between previous valve surgery and PM implantation was 6.4 years in 12 cases after initial valve surgery and 2.3 years in nine after second valve surgery. Postoperative course after PM implantation was almost good, but one case was died due to critical arrhythmia. And one case underwent re-MVR because of mitral bioprosthesis dysfunction and one, without anticoagulant after OMC, was complicated cerebral infarction.     

Benchmarking a multi-access system

This paper describes an attempt to test the multi-access capabilities of three widely differing systems. Some of the difficulties encountered in trying to find a common approach are detailed.     

Effects of hypertension on the static mechanical properties and chemical composition of the rat aorta

The contributions of the relative radius, relative wall thickness, incremental strain, incremental elastic modulus, and medial scleroprotein content to the static elastic properties of the rat aortic wall have been examined in three groups of rats. Controls, rats made hypertensive at four weeks of age, and rats whose blood pressure was lowered after 6 weeks hypertension, were studied. The results show evidence of adaptive changes in the aorta of hypertensive animals, and that irreversible alterations in the mechanical properties of the wall may be induced by a brief period of hypertension. A direct relationship between aortic medial scleroprotein content and the elastic properties of the wall is demonstrated.     

Derepressed alloantigen in transplacentally induced lung tumor coded for by H-2 linked gene

A transplacentally induced lung tumor of strain C3Hf mice grows progressively when transplanted to (C3Hf X A)F1 hybrid mice but not when transplanted to C3Hf recipients. Progressive tumor growth occurs in [(C3Hf X A)F1 X C3Hf] backcross mice inheriting the H-2a haplotype from the F1 parent. Furthermore, radioresistant immunity to the lung tumor can be induced in C3Hf mice by immunization with normal tissue of B10.A and B10.A(2R) but not of B10 or B10.A(5R) strain mice.     

The importance of neonatal asphyxia and caesarean section as risk factors for neonatal respiratory disorders in an unselected population

The risk of neonatal respiratory disorders was calculated in an unselected, total population together with the relative contributions of some factors found associated with an increased risk. Postnatal asphyxia, expressed as a low one minute Apgar score, and low gestational age were substantially, independent risk factors. Caesarean section added, though less markedly, to the risk of the above disorders.     

Phonotactic influences on short-term memory

The impact of phonotactic probabilities on serial recall was investigated in a series of experiments. In Experiments 1A and 1B, 7 and 8 year olds were tested on their serial recall of monosyllabic words and of nonwords varying in phonotactic frequencies. A recall advantage to words over nonwords remained when stimuli were balanced for phonotactic probability, but nonword recall showed superior accuracy for high over low probability nonwords, as in Experiment 2. The nonword frequency effect appears to reflect the frequency of constituent syllables rather than biphones. Both lexicality and high phonotactic frequency led to increased proportions of full over partial recall of the memory stimuli. These findings indicate that decayed memory traces in phonological short-term memory can be reconstructed using either lexical or phonotactic knowledge.