Citations

AbstractPatients with myelofibrosis with myeloid metaplasia (MMM) often experience debilitating constitutional symptoms such as drenching night sweats, profound fatigue, unexplained fevers, and unintentional weight loss. Tumor necrosis factor (TNF) contributes to organ fibrosis and hypercatabolic symptoms in a variety of disease states. We conducted an open-label pilot study of etanercept, a soluble TNF receptor, administered at a dose of 25 mg subcutaneously twice weekly for up to 24 weeks in 22 patients with MMM. Of 20 evaluable patients, 12 (60%) experienced an improvement in constitutional symptoms, and 4 (20%) had an objective response (improvement in peripheral cytopenias or spleen size). The degree of marrow fibrosis was unchanged, and only minor changes in overall marrow cellularity were observed. Toxicity was mild, with injection site reactions (20%) and minor infections (10%) as the most common side effects. One patient developed reversible pancytopenia. Etanercept may be useful for palliation of constitutional symptoms in MMM.

AbstractThe ashen (ash) mouse, a model for Hermansky-Pudlak syndrome (HPS) and for a subset of patients with Griscelli syndrome, presents with hypopigmentation, prolonged bleeding times, and platelet storage pool deficiency due to a mutation which abrogates expression of the Rab27a protein. Platelets of mice with the ashen mutation on the C3H/HeSnJ inbred strain background have greatly reduced amounts of dense granule components such as serotonin and adenine nucleotides though near-normal numbers of dense granules as enumerated by the dense granule-specific fluorescent dye mepacrine. Thus, essentially normal numbers of platelet dense granules are produced but the granule interiors are abnormal. Collagen-mediated aggregation of mutant platelets is significantly depressed. No abnormalities in the concentrations or secretory rates of 2 other major platelet granules, lysosomes and alpha granules, were apparent. Similarly, no platelet ultrastructural alterations other than those involving dense granules were detected. Therefore, Rab27a regulates the synthesis and secretion of only one major platelet organelle, the dense granule. There were likewise no mutant effects on levels or secretion of lysosomal enzymes of several other tissues. Together with other recent analyses of the ashen mouse, these results suggest a close relationship between platelet dense granules, melanosomes of melanocytes and secretory lysosomes of cytotoxic T lymphocytes, all mediated by Rab27a. Surprisingly, the effects of the ashen mutation on platelet-dense granule components, platelet aggregation, and bleeding times were highly dependent on genetic background. This suggests that bleeding tendencies may likewise vary among patients with Griscelli syndrome and HPS with Rab27a mutations.

Background— Although aortic valve replacement can be performed at an acceptable risk level in selected patients with left ventricular systolic dysfunction and low-output, low-gradient aortic stenosis, not all patients presenting with these hemodynamics will benefit from the operation. Some patients may have only mild aortic stenosis, despite a small calculated valve area. We report on the clinical utility of diagnostic dobutamine stimulation during cardiac catheterization in these diagnostically challenging patients. Methods and Results— Thirty-two patients with low-output, low-gradient aortic stenosis and an ejection fraction <40% had dobutamine infusion in the catheterization laboratory. On the basis of the results of the dobutamine test, 21 patients underwent aortic valve replacement. All patients with a final aortic valve area ≤1.2 cm 2 at peak dobutamine infusion and a mean gradient of >30 mm Hg were found to have severe calcific aortic stenosis at operation. In the 15 patients in whom contractile reserve was identified during dobutamine challenge (increase in stroke volume >20%), 1 patient died perioperatively (7% mortality) and 12 patients were alive in New York Heart Association class I or II status at follow-up. Conclusions— In patients with left ventricular systolic dysfunction and aortic stenosis with a low output and a low mean gradient, dobutamine challenge may aid in selecting those who would benefit from an aortic valve operation.

ABSTRACT Gene therapy in eukaryotes has met many obstacles. Research into the design of suitable nonviral vectors has been slow. To our knowledge, no nonviral vector has been proposed that allows for the possibility of highly efficient, site‐selective integration into the genome of mammalian cells. On the basis of prior studies investigating the components necessary for transposon, retrovirus‐like retrotransposon, and retroviral integration, we propose a nonviral system that would potentially allow for site‐selective, efficient integration into the mammalian genome. Transposons have been developed that can transform a variety of cell lines. For example, the Sleeping Beauty transposon (SB) can transform a wide range of vertebrate cells from fish to human, and it mediates stable integration and long‐term transgene expression in mice. However, the efficiency of transposition varies significantly among cell lines, suggesting the possible involvement of host factors in SB transposition. Here, we propose the use of a chimeric transposase (i.e., transposase‐host DNA binding domain) to bypass the potential requirement of a host DNA‐directing factor (or factors) for efficient, site‐selective integration. We also discuss another potential method of docking the transposonbased vector adjacent to the host DNA, utilizing repetitive sequences for homologous recombination to promote efficient site‐selective integration, as well as other site‐selective nonviral approaches.—Kaminski, J. M., Huber, M. R., Summers, J. B., Ward, M. B. Design of a nonviral vector for site‐selective, efficient integration into the human genome. FASEB J . 16, 1242–1247 (2002)

Many of the mechanisms that govern T-cell homeostasis remain obscure. Here we report that repeated administration of synthetic oligodeoxynucleotides containing unmethylated cytosine-guanine motifs (CpG-ODN) into mice induces a systemic antigen-independent expansion of naive and memory T cells in a full T-cell compartment. Expansion of T cells was observed on both CD4+ and CD8+ T-cell subsets and was produced not by inducing the proliferation of the cells but by preventing their death. The antiapoptotic effects of CpG-ODN on T cells were observed against activation-induced death and growth factor withdrawal–mediated death. The ability of CpG-ODN to protect T cells from these forms of death was associated with the up-regulation of antiapoptotic gene products including c-FLIP, bcl-xL, and, to some extent, bcl-2. The effect of CpG-ODN on naive and memory T cells required the expression of CD28 and was not dependent on the presence of B lymphocytes, suggesting that other antigen-presenting cells that respond to CpG-ODN, such as dendritic cells, may provide antiapoptotic signals to T cells in an antigen-independent but CD28/B7-dependent fashion. The present findings suggest that CpG-ODN can disrupt normal T-cell homeostasis not by acting as a mitogen but by preventing T-cell death that normally takes place as a mechanism to maintain steady-state levels of T cells. These findings support a potential means to expeditiously replenish and maintain the peripheral lymphocyte population after severe immunodepletion such as that which occurs in HIV-infected individuals and individuals undergoing cytoablative therapies.

Objective— Occurrence of arterial thrombosis secondary to vascular disease in an individual is not easily predicted. After establishing that this poor predictability arises at least in part from an intrinsic thrombosis propensity of the individual, we sought to determine whether the propensity for arterial thrombosis is governed by blood or arterial wall factors. Methods and Results— To evaluate the variability arising from the blood, autologous 111 In-labeled platelet deposition was measured after high-shear perfusion of compressed aortic strips, prepared from a single pig, with heparinized blood from 25 pigs. To evaluate the variability arising from the vessel wall, aortic strips from 8 pigs were superfused with blood from a single animal. Blood samples from 25 animals superfused over aortic substrate from a single source yielded a 24-fold range of platelet deposition. In contrast, when aortic substrates from 8 different animals were superfused with blood from a single animal, platelet deposition spanned a 3-fold range. Platelet deposition was significantly correlated with whole-blood lymphocyte counts and with platelet counts . Conclusions— Individual propensity for arterial thrombosis in pigs is more greatly influenced by blood components than by elements within the arterial wall.

The National Heart, Lung, and Blood Institute (NHLBI) recently convened the Heart and Lung Xenotransplantation Working Group to identify hurdles to the clinical application of xenotransplantation, defined as the use of animal organs or tissue for transplantation, and to recommend possible solutions to these problems. The group consisted of experts in xenotransplantation from academia, industry, and federal agencies, and the discussions focused on those areas within the mission of the NHLBI. The areas covered included immunologic and physiological barriers to xenotransplantation, the limitations of the current animal models, the need for collaboration among groups, the high costs of studies using nonhuman primates and genetic engineering of pigs, and the unique problems of lung xenotransplantation. This report is a summary of those discussions.