Hematopoiesis in mice lacking the entire granulocyte-macrophage colony- stimulating factor/interleukin-3/interleukin-5 functions

Interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-5 are major hematopoietic cytokines produced by activated T cells and exhibit similar biologic activities by signaling through a common receptor subunit (beta c). Mice lacking beta c show a pulmonary alveolar proteinosis-like disease and reduced numbers of peripheral eosinophils, which are explained by the lack of GM-CSF and IL-5 function, respectively. However, beta c-deficient hematopoietic cells do respond to IL-3 normally, probably through an additional beta subunit of the IL-3 receptor (beta IL3) that is present in the mouse. Thus, almost normal hematopoiesis in beta c-deficient mice may be caused by functional redundancy between IL-3 and GM-CSF. To clarify the role of the entire IL-3/GM-CSF/IL-5 system in hematopoiesis in vivo, we crossed the beta c mutant mice with mice deficient for IL-3 ligand to generate mice lacking the entire IL-3/GM-CSF/IL-5 functions. The double- mutant mice were apparently normal and fertile. The severity of the lung pathology in the beta c/IL-3 double-mutant mice showed normal hemodynamic parameters except for reduced numbers of eosinophils and the lack of eosinophilic response to parasites, which were also found in beta c mutant mice. The immune response of the beta c/IL-3 double- mutant mice to Listeria mono-cytogenes was normal, as was hematopoietic recovery after administration of the cytotoxic drug, 5-fluorouracil. Although it has been believed that IL-3/GM-CSF/IL-5 produced by activated T cells play a major role in expansion of hematopoietic cells in emergency, our results indicate that the entire function of IL-3/GM- CSF/IL-5 is dispensable for hematopoiesis in emergency as well as in the steady state. Thus, there must be an alternative mechanism to produce blood cells in both situations.     

Thin spinal or biopsy needle guidance

The thin needles that are used for myelography or biopsy are easily deflected in the body. We describe a simple method used to guide the tip of these needles to the target area using needle-hub rotation. This procedure was successfully used in more than 260 direct C1-C2 punctures for cervical myelography.     

Near-normal circulatory survival of rabbit red cells exposed to high levels of Ca and ionophore in vitro

The belief is widely held, on the basis of indirect evidence, that a substantial, even brief elevation of red cell Ca content must result in a marked shortening of circulatory survival. To test this notion directly, we exposed rabbit red cells in vitro to the ionophore A23187 and Ca so as to produce sustained uniform cell Ca levels of 40 to 360 mumol/L cells for one to 60 minutes, and compared the survival of the Ca-loaded cells in vivo with that of ionophore-treated controls, simultaneously, in the same rabbits. Despite marked reductions in cell adenosine triphosphate and dehydration of the Ca-exposed cells prior to reinfusion, the majority of cells, all of which had experienced these high cytoplasmic Ca levels, showed normal or near-normal survival in the circulation.     

mdx muscle pathology is independent of nNOS perturbation

In skeletal muscle, neuronal nitric oxide synthase (nNOS) is anchored to the sarcolemma via the dystrophin-glycoprotein complex. When dystrophin is absent, as in Duchenne muscular dystrophy patients and in mdx mice, nNOS is mislocalized to the interior of the muscle fiber where it continues to produce nitric oxide. This has led to the hypothesis that free radical toxicity from mislocalized nNOS may contribute to mdx muscle pathology. To test this hypothesis directly, we generated mice devoid of both nNOS and dystrophin. Overall, the nNOS- dystrophin null mice maintained the dystrophic characteristics of mdx mice. We evaluated the mice for several features of the dystrophic phenotype, including membrane damage and muscle morphology. Removal of nNOS did not alter the extent of sarcolemma damage, which is a hallmark of the dystrophic phenotype. Furthermore, muscle from nNOS-dystrophin null mice maintain the histological features of mdx pathology. Our results demonstrate that relocalization of nNOS to the cytosol does not contribute significantly to mdx pathogenesis.