Changes in Clara cell 10 kDa protein (CC10)-positive cell distribution in acute lung injury following repeated lipopolysaccharide challenge in the rat.

Clara cell 10 kDa protein (CC10) is the major secretory protein of Clara cells and is thought to play a protective role in the lung owing to its anti-inflammatory properties. There is little information on the anatomical distribution of CC10-positive cells in rat lung following lipopolysaccharide (LPS) challenge. We have determined the expression of CC10 along the tracheobronchial tree in saline-treated and LPS-treated rats. Saline-treated rats showed sporadic CC10 staining in central airways and abundant staining in bronchioles. In transitional airways, most cells were positive except for squamous cells. Following LPS challenge, there was a reduction in staining in the upper airways but little change within bronchioles. Squamous epithelia within the transitional airways now showed positive staining. These cells also co-stained for pancytokeratin and appeared to co-localize with surfactant D- and Ki67-positive cells, indicating the presence of a dedifferentiated cell type with both epithelial and pneumocyte phenotypes. These data show that diffuse inflammatory injury results in generalized loss of CC10 in central airways. Conversely, the transitional airways showed evidence of a dedifferentiated population of squamous cells that now stained for CC10. We hypothesize that this is an attempt by peripheral lung to maintain alveolar sac integrity during an inflammatory episode.

Effects of kaolin particle film on Myzus persicae (Hemiptera: Aphididae) behaviour and performance.

The emergence of resistance mechanisms to, and revocation of, many insecticides used in the control of the polyphagus aphid pest, Myzus persicae (Sulzer), has increased the pressure to develop novel approaches for the control of the pest in many crops. Kaolin-based particle films provide a physical barrier against insect pests and show considerable potential for controlling M. persicae. We conducted a series of laboratory experiments to investigate the mode of action of kaolin against aphids. The material appeared to have no direct effect on M. persicae; spraying adult aphids with aqueous kaolin suspension had no significant impact on their subsequent survival or reproduction on untreated plants. Similarly, when aphids were placed on kaolin-treated host-plants (Brassica oleracea), their performance (survival, growth rate and reproduction) was not significantly different from aphids on untreated plants. However, when M. persicae were given a choice between kaolin-treated and untreated (or water solvent-treated) leaf areas, both adults and nymphs exhibited a significant preference for non-kaolin-treated host-plant material. Rejection of kaolin-treated plant material occurred very rapidly (within 20 min) and this behavioural effect may be related to the efficacy of kaolin in controlling aphids under field conditions.

Electrocardiographic and other cardiac anomalies in beta-glucuronidase-null mice corrected by nonablative neonatal marrow transplantation.

Cardiovascular manifestations of lysosomal storage disease (LSD) are a significant health problem for affected patients. Infantile-onset cardiac disease, because of its rapid progression, is usually treated symptomatically. Therapy in older patients includes valve replacement and bone marrow (BM) transplantation, both of which are life threatening in the already debilitated patients. Enzyme replacement therapy has potential benefit but has not yet been demonstrated to provide long-term relief for cardiac disease. Here, we demonstrate prevention of severe cardiac manifestations in beta-glucuronidase (GUSB) null mice BM-transplanted i.v. as neonates without myeloablative pretreatment. The mice, a model of mucopolysaccharidosis type VII (MPSVII, Sly syndrome), develop progressive LSD unless provided with GUSB early in life. The BM recipients retained GUSB+ donor cells in the peripheral blood and heart until necropsy at > or = 11 months of age. The enzyme beta-hexosamindase increased in tissues of GUSB null MPSVII mice was reduced significantly (P = 0.001) in treated MPSVII hearts. Electrocardiography demonstrated normalization of heart rate, PR, PQ, and QRS intervals in BM recipients. Storage was markedly reduced in the stroma of heart valves, adventitial cells of the aortic root, perivascular and interstitial cells of the myocardium, and interstitial cells of the conduction tissue. Heart/body weight ratio normalized. The aortic root was still grossly distended, and the conductive myocytes retained storage, suggesting neither plays a major role in ECG normalization. We conclude that transplantation of MPSVII neonates without toxic intervention can prevent many of the cardiovascular manifestations of LSD.

Donor cell replacement in mice transplanted in utero is limited by immune-independent mechanisms.

In utero transplantation (IUTx) therapy with allogeneic cells results in negligible peripheral blood (PBL) chimerism in nonablated humans with progressive diseases. IUTx has been successful only in immunocompromised fetuses. Because early treatment has great potential for halting disease progression, mechanisms preventing cell expansion must be identified and corrected. The hypothesis that factors in addition to allogenicity are responsible for low-level expansion is tested here by transplanting congenic cells into nonablated normal and mucopolycaccharidosis type VII (MPSVII) murine fetuses. MPSVII mice lack the enzyme beta-glucuronidase (GUSB-), accumulate glycosaminoglycans, and progressively develop severe storage disease. Low levels of enzyme can reverse storage. Evidence presented elsewhere showed that allogeneic donor cells overexpressing GUSB are negligible and their corrective effects are lost post-IUTx in MPSVII mice. We find that (1) congenic donor PBL cells, like allogeneic cells, are negligible in PBL of normal GUSB+ and MPSVII GUSB- hosts post-IUTx; (2) congenic, unlike allogeneic cells, are retained long term in both GUSB+ and GUSB- recipients; and (3) sufficient GUSB is produced to alleviate storage for up to 11.5 months in multiple tissues of GUSB- hosts. GUSB+ and GUSB- animals repopulate to a similar extent, indicating that donor GUSB enzyme does not initiate an immune response in the MPSVII null recipients. We conclude that the initial expansion of congenic and allogeneic cells is limited post-IUTx by non-immune-related mechanisms and the level of PBL cells is not necessarily indicative of graft failure following congenic IUTx. The mechanism limiting initial expansion may differ from that supporting long-term cell retention.

Reduced incidence of thrombosis in mice with hereditary spherocytosis following neonatal treatment with normal hematopoietic cells.

Thrombosis is a life-threatening complication of hemolytic anemia in humans. Cardiac thrombi are present in all adult alpha-spectrin-deficient (sph/sph) mice with severe hereditary spherocytosis, providing a model for events preceding thrombosis. The current study evaluated (1) the timing of thrombosis initiation and (2) the effect of postnatal transplantation of normal cells on life span and thrombotic incidence in adult mice. Thrombi are detected histologically following necropsy in untreated sph/sph mice of various ages and are not observed until 6 weeks of age. Thrombotic incidence increases from 50% at 6 to 7 weeks of age to 100% at 9 weeks of age. As a potential therapy, nonablated sph/sph neonates were transfused with either genetically marked normal peripheral blood (PB), bone marrow (BM), or both and assessed for donor cells and thrombosis. A single transfusion of PB, with or without BM, significantly increases the percentage of sph/sph mice that survive to weaning (4 weeks of age). Replacement in all sph/sph recipients is limited to red blood cells (RBCs). RBCs derived from donor PB are lost within 5 weeks. PB plus BM prolongs high-level donor PB cell production better than BM alone. Thrombotic incidence is significantly reduced in all sph/sph mice treated with PB, BM, or both. Hence, the presence of normal blood cells in the peripheral circulation of neonatal and adult sph/sph mice rescues the former and abrogates the development of thrombosis in the latter. (Blood. 2001;97:3972-3975)

Targeted disruption of the nitric oxide synthase 2 gene protects against ischaemia/reperfusion injury to skeletal muscle.

To provide definitive insight into the complicated roles of the nitric oxide synthase (NOS) enzymes in ischaemia/reperfusion (I/R) injury of skeletal muscle, experiments were undertaken in mice with targeted disruption of the inducible NOS (NOS-2 KO) isoform, compared with the wild-type mouse strain. The degree of I/R injury in the NOS-2 KO mice was attenuated relative to that in the wild-type strain. After 70 min of ischaemia (24 h reperfusion), nitroblue tetrazolium (NBT) staining of skeletal muscle showed significant necrosis (40%) in wild-type mice, whilst in NOS-2 KO mice, ischaemia could be prolonged to 90 min before significant necrosis (38%) was apparent. Specific enzyme activities of the mitochondrial respiratory chain enzymes, measured in skeletal muscle homogenates, suggested that direct inhibition of the enzymes is not causal in the I/R injury. Immunohistological examination of skeletal muscle for NOS-2 showed its induction selectively in mast cells. In vitro experiments using bone marrow-derived mast cells showed that NOS-2 induction was associated with increased degranulation of mast cells. These findings suggest that NO generated by induction of NOS-2 has a deleterious effect in I/R injury of skeletal muscle and that NO exerts its damaging effect through factors released by degranulation of mast cells.

Nitric oxide synthase II gene disruption: implications for tumor growth and vascular endothelial growth factor production.

The expression of a primary initiator of tumor angiogenic responses, vascular endothelial growth factor (VEGF), may be induced by nitric oxide (NO) in carcinoma cells. However, the net impact of NO on carcinogenesis remains unclear, because manipulation of NO levels has been shown to either stimulate or inhibit tumor growth. We have investigated the relationship between inducible NO synthase (NOS II), VEGF expression, and growth of B16-F1 melanoma over 14 days in wild-type (NOS II+/+) mice and in those in which the gene for NOS II has been deleted (NOS II-/-). B16-F1 tumor growth was measured as wet weight of the excised tissue. Tumor NOS II and VEGF localization were evaluated by immunohistochemistry, and VEGF mRNA levels were measured by Northern blot analysis. In NOS II+/+ mice inoculated with B16-F1 melanoma cells, macroscopic tumors were always observed at 14 days; however, 22% of NOS II-/- mice had no detectable tumor mass. Immunoreactive NOS II was detected in tumor cells of tumors grown in NOS II+/+ but not in NOS II-/- mice. Although immunoreactive VEGF was detected in the granules of tumor-associated mast cells from both NOS II+/+ and NOS II-/- mice, VEGF mRNA expression in tumors from NOS II-/- was half that in NOS II+/+ mice. Neither NOS II inhibition, exogenous NO, nor peroxynitrite influenced DNA synthesis in culture B16-F1 melanoma cells. The NO donor did not alter either VEGF mRNA levels or degranulation in cultures of the mast cell line RBL-2H3, but peroxynitrite increased both VEGF mRNA expression and degranulation. We conclude that host expression of NOS II contributes to induction of NOS II in the tumor and to melanoma growth in vivo, possibly by regulating the amount and availability of VEGF.

Inducible nitric oxide synthase (iNOS) activity promotes ischaemic skin flap survival.

We have examined the role of nitric oxide (NO) in a model of functional angiogenesis in which survival of a skin flap depends entirely on angiogenesis to provide an arterial blood supply to maintain tissue viability. The different effects of nitric oxide synthase (NOS) inhibitors on rat skin flap survival appeared to be explained on the basis of their NOS isoform selectivity. Skin flap survival was decreased by iNOS-selective (inducible NOS) inhibitors, S-methyl-isothiourea, aminoguanidine and aminoethylthiorea; unaffected by the non-selective inhibitor nitro-imino-L-ornithine; and enhanced by the cNOS (constitutive NOS, that is endothelial NOS (eNOS) and neuronal NOS (nNOS)) inhibitor, nitro-L-arginine methyl ester. Skin flap survival was reduced in mice with targeted disruption of the iNOS gene (iNOS knockout mice), and the administration of nitro-L-arginine methyl ester significantly increased flap survival in iNOS knockout mice (P<0.05). iNOS immunoreactivity was identified in mast cells in the angiogenic region. Immunoreactive vascular endothelial growth factor (VEGF) and basic fibroblast growth factor were also localized to mast cells. The combination of interferon-gamma and tumour necrosis factor-alpha induced NO production and increased VEGF levels in mast cells cultured from bone marrow of wild-type, but not iNOS KO mice. The increased tissue survival associated with the capacity for iNOS expression may be related to iNOS-dependent enhancement of VEGF levels and an ensuing angiogenic response. Our results provide both pharmacological and genetic evidence that iNOS activity promotes survival of ischaemic tissue.

Reactive oxygen species mediate endothelium-dependent relaxations in tetrahydrobiopterin-deficient mice.

(6R)-5,6,7,8-Tetrahydro-biopterin (H(4)B) is essential for the catalytic activity of all NO synthases. The hyperphenylalaninemic mouse mutant (hph-1) displays 90% deficiency of the GTP cyclohydrolase I, the rate-limiting enzyme in H(4)B synthesis. A relative shortage of H(4)B may shift the balance between endothelial NO synthase (eNOS)-catalyzed generation of NO and reactive oxygen species. Therefore, the hph-1 mouse represents a unique model to assess the effect of chronic H(4)B deficiency on endothelial function. Aortas from 8-week-old hph-1 and wild-type mice (C57BLxCBA) were compared. H(4)B levels were determined by high-performance liquid chromatography and NO synthase activity by [(3)H]citrulline assay in homogenized tissue. Superoxide production by the chemiluminescence method was measured. Isometric tension was continuously recorded. The intracellular levels of H(4)B as well as constitutive NO synthase activity were significantly lower in hph-1 compared with wild-type mice. Systolic blood pressure was increased in hph-1 mice. However, endothelium-dependent relaxations to acetylcholine were present in both groups and abolished by inhibition of NO synthase with N(G)-nitro-L-arginine methyl ester as well. Only in hph-1 mice were the relaxations inhibited by catalase and enhanced by superoxide dismutase. After incubation with exogenous H(4)B, the differences between the 2 groups disappeared. Our findings demonstrate that H(4)B deficiency leads to eNOS dysfunction with the formation of reactive oxygen species, which become mediators of endothelium-dependent relaxations. A decreased availability of H(4)B may favor an impaired activity of eNOS and thus contribute to the development of vascular diseases.

Nonablative neonatal marrow transplantation attenuates functional and physical defects of beta-glucuronidase deficiency.

The toxicity of preparative regimens render neonatal bone marrow transplantation (BMT) for progressive childhood diseases a controversial treatment. Ablative BMT in neonatal mice with or without the lysosomal storage disease mucopolysaccharidosis type VII (MPS VII) show high morbidity and developmental disruption of both brain and bone structure. In this investigation, BMT was performed with a high dose of congenic, normal bone marrow into nonablated newborn mice. Recipients had lifelong, multilineage, peripheral blood chimerism with the donor beta-glucuronidase-positive (GUS(+)) cells that was both well tolerated and therapeutic. Three daily injections of normal adult marrow increased the average life span by at least 6 months and corrected the functional breeding deficits typical of the MPS VII mice. Twelve months after injection, several structural features of femurs were more like that of normal mice than of untreated MPS VII mice. Periosteal circumference and bone cortical thickness were significantly improved in males and cortical density did not differ significantly from values in normal females. Significant reduction of lysosomal glycosaminoglycan storage corresponded directly with GUS enzyme activity and percentage of histochemically GUS(+) cells in visceral organs and hematopoietic tissues such as thymus, spleen, peripheral blood, and bone marrow. By all criteria tested, BMT into neonatal MPS VII mice in the absence of any preparative regimen is a successful therapy.

Na,K-ATPase in skeletal muscle: two populations of beta-spectrin control localization in the sarcolemma but not partitioning between the sarcolemma and the transverse tubules.

We used immunological approaches to study the factors controlling the distribution of the Na,K-ATPase in fast twitch skeletal muscle of the rat. Both alpha subunits of the Na,K-ATPase colocalize with beta-spectrin and ankyrin 3 in costameres, structures at the sarcolemma that lie over Z and M-lines and in longitudinal strands. In immunoprecipitates, the alpha1 and alpha2 subunits of the Na,K-ATPase as well as ankyrin 3 associate with beta-spectrin/alpha- fodrin heteromers and with a pool of beta-spectrin at the sarcolemma that does not contain alpha-fodrin. Myofibers of mutant mice lacking beta-spectrin (ja/ja) have a more uniform distribution of both the alpha1 and alpha2 subunits of the Na,K-ATPase in the sarcolemma, supporting the idea that the rectilinear sarcomeric pattern assumed by the Na,K-ATPase in wild-type muscle requires beta-spectrin. The Na,K-ATPase and beta-spectrin are distributed normally in muscle fibers of the nb/nb mouse, which lacks ankyrin 1, suggesting that this isoform of ankyrin is not necessary to link the Na,K-ATPase to the spectrin-based membrane skeleton. In immunofluorescence and subcellular fractionation experiments, the alpha2 but not the alpha1 subunit of the Na,K-ATPase is present in transverse (t-) tubules. The alpha1 subunit of the pump is not detected in increased amounts in the t-tubules of muscle from the ja/ja mouse, however. Our results suggest that the spectrin-based membrane skeleton, including ankyrin 3, concentrates both isoforms of the Na,K-ATPase in costameres, but that it does not play a significant role in restricting the entry of the alpha1 subunit into the t-tubules.

Defective spectrin integrity and neonatal thrombosis in the first mouse model for severe hereditary elliptocytosis.

Mutations affecting the conversion of spectrin dimers to tetramers result in hereditary elliptocytosis (HE), whereas a deficiency of human erythroid alpha- or beta-spectrin results in hereditary spherocytosis (HS). All spontaneous mutant mice with cytoskeletal deficiencies of spectrin reported to date have HS. Here, the first spontaneous mouse mutant, sph(Dem)/ sph(Dem), with severe HE is described. The sph(Dem) mutation is the insertion of an intracisternal A particle element in intron 10 of the erythroid alpha-spectrin gene. This causes exon skipping, the in-frame deletion of 46 amino acids from repeat 5 of alpha-spectrin and alters spectrin dimer/tetramer stability and osmotic fragility. The disease is more severe in sph(Dem)/sph(Dem) neonates than in alpha-spectrin-deficient mice with HS. Thrombosis and infarction are not, as in the HS mice, limited to adults but occur soon after birth. Genetic background differences that exist between HE and HS mice are suspect, along with red blood cell morphology differences, as modifiers of thrombosis timing. sph(Dem)/sph(Dem) mice provide a unique model for analyzing spectrin dimer- to-tetramer conversion and identifying factors that influence thrombosis.

Downeast anemia (dea), a new mouse model of severe nonspherocytic hemolytic anemia caused by hexokinase (HK(1)) deficiency.

A new spontaneous mutation in the A/J inbred mouse strain, downeast anemia (dea), causes severe hemolytic anemia with extensive tissue iron deposition and marked reticulocytosis. The anemia is present at birth and persists throughout life. The defect is inherited as an autosomal recessive and is transferable through bone marrow stem cells. The red cell morphology is consistent with a nonspherocytic hemolytic anemia, suggestive of a red cell enzymopathy. In linkage analysis, dea is nonrecombinant with the hexokinase-1 gene (Hk1) on mouse Chromosome 10. Expression of Hk1 is markedly decreased in dea erythroid tissues, and the transcript produced is larger than normal. Hexokinase enzyme activity is significantly decreased in dea tissues, including red cells, spleen, and kidney. Southern blot analyses revealed approximately 5.5 kb of additional sequence in the 5' portion of the dea Hk1 gene, which was identified by direct sequencing as an early transposon (ETn) insertion in intron 4. ETn insertions disrupt genes in several mouse models by a variety of mechanisms, including aberrant splicing of ETn sequences into the mRNA. We conclude that the primary gene defect in the dea mutation is in Hk1 and that dea is a model of generalized hexokinase deficiency, the first such model identified to date.

In utero fetal liver cell transplantation without toxic irradiation alleviates lysosomal storage in mice with mucopolysaccharidosis type VII.

Lysosomal storage diseases, such as Mucopolysaccharidosis type VII (MPS VII), cause progressive loss of mobility and intellect and result in early death. Treatment of progressive diseases must occur before the blood-brain barrier closes. In MPS VII mice, normal donor hematopoietic cells secrete the missing enzyme beta-glucuronidase (GUSB) that reverses disease manifestations. Correction of lysosomal storage is limited to the visceral organs unless transplantation is preceded by high-dose irradiation. We hypothesize that irradiation opens the blood-brain barrier allowing passage of corrective cells. Here we transplanted genetically myeloablated MPS VII fetuses to determine whether earlier treatment without toxic irradiation is systemically corrective. Cells with a selective advantage in utero were identified. Donor fetal liver cells (FLC), a substitute for difficult to obtain murine cord blood cells, were increased 10-fold in the host peripheral blood over equivalent numbers of adult marrow cells injected simultaneously and were stable long term in both primary and secondary hosts. GUSB- MPS VII fetuses injected with GUSB+ FLC were assessed longitudinally after birth. Donor FLC replaced host stem cell descendants, prolonged life dramatically, and reduced bone dysplasia and lysosomal storage in all tissues long term. GUSB, donor leptomeningeal cells, and microglia were present in the brain at 11 months postinjection. Lysosomal storage in cortical neurons and glia, although not completely corrected, was reduced. We conclude that in utero intervention without toxic pretreatment in this model reduces the storage disease long term and improves the length and quality of life despite exerting only minor effects on the brain.

TNF-alpha induces osteoclastogenesis by direct stimulation of macrophages exposed to permissive levels of RANK ligand.

While TNF-alpha is pivotal to the pathogenesis of inflammatory osteolysis, the means by which it recruits osteoclasts and promotes bone destruction are unknown. We find that a pure population of murine osteoclast precursors fails to undergo osteoclastogenesis when treated with TNF-alpha alone. In contrast, the cytokine dramatically stimulates differentiation in macrophages primed by less than one percent of the amount of RANKL (ligand for the receptor activator of NF-kappaB) required to induce osteoclast formation. Mirroring their synergistic effects on osteoclast differentiation, TNF-alpha and RANKL markedly potentiate NF-kappaB and stress-activated protein kinase/c-Jun NH(2)-terminal kinase activity, two signaling pathways essential for osteoclastogenesis. In vivo administration of TNF-alpha prompts robust osteoclast formation in chimeric animals in which ss-galactosidase positive, TNF-responsive macrophages develop within a TNF-nonresponsive stromal environment. Thus, while TNF-alpha alone does not induce osteoclastogenesis, it does so both in vitro and in vivo by directly targeting macrophages within a stromal environment that expresses permissive levels of RANKL. Given the minuscule amount of RANKL sufficient to synergize with TNF-alpha to promote osteoclastogenesis, TNF-alpha appears to be a more convenient target in arresting inflammatory osteolysis.

Spontaneous fracture (sfx): a mouse genetic model of defective peripubertal bone formation.

A new mouse model of stage-specific bone growth failure and fracture has been recovered as an autosomal recessive mutation, designated spontaneous fracture (sfx). The sfx/sfx mice are phenotypically normal until shortly after weaning, when reduced mobility and impaired somatic growth are first noted. By 6 weeks of age, body, spleen, and thymus weights, as well as hematocrits and serum calcium, inorganic phosphate, total alkaline phosphatase, insulin-like growth factor-I, and osteocalcin levels are decreased. The sfx/sfx mice also show reduced femoral cortical density and diaphyseal circumference, as well as a paucity of mature osteoblasts on bone surfaces. Histological analyses of the femur and tibia in the mutants show subtle reduction of chondrocyte numbers in epiphyseal-plate columns, reduction of matrix, and near absence of osteoid below the differentiated chondrocytes. Trabeculae in proximal tibiae, iliacs, and vertebral bodies are sparse and thin. Cortical bone thickness of mutants is markedly thinned in all sites examined. By 7-8 weeks, radiographic films routinely show spontaneous impact fractures of the distal femur accompanied by callus formation, whereas complete fractures are less commonly observed. Volumetric bone mineral density (BMD) of mutant femurs is similar to +/? littermates in the center of the femoral diaphysis, but BMD declines as either end of the femoral diaphysis is approached. We have mapped the gene responsible for this phenotype to central Chromosome 14. Reduced bone mass, impaired bone formation, abnormalities of bone architecture, and a disposition to spontaneous fracture identify sfx/sfx mice as a useful model for understanding the mechanisms responsible for peripubertal bone formation.

Amelioration of severe hereditary spherocytosis in nonablated adult mice by marrow transplantation.

Human severe hereditary spherocytosis (sHS) is life threatening and transfusion dependent. sHS is lethal within 6 days of birth for 99% of jaundiced (ja/ja) mice, making these mice excellent models for early therapeutic interventions. Nonablated ja/ja neonates simultaneously transfused and given intravenous injections of normal marrow become chimeric for donor cells. Significant improvement of red blood cell parameters occurs but is temporary because the donor marrow-derived cells gradually disappear from the circulation. The average lifespan, however, is increased to 8.7 months. We postulate that donor cells are diluted by rapidly proliferating host cells during postnatal growth. Here, we test this hypothesis by determining whether treatment of adults improves long-term therapy. Nonablated ja/ja adults rescued by a single neonatal transfusion were injected intravenously with 1 x 10(10) normal, genetically marked donor marrow cells/kg body weight. Donor cell implantation and blood parameters were monitored periodically and tissue histopathology was determined at necropsy.sHS recipients with 100% donor erythroid cells have significantly improved red blood cell counts throughout life when compared with ja/ja controls transfused once at birth. Total serum iron and bilirubin levels are corrected in ja/ja marrow recipients. Donor-implanted HS mice necropsied at 16 to 21 months of age have normal mean cell hemoglobin concentration and dramatically decreased tissue iron deposits. Reticulocyte counts but not red cell counts normalize, suggesting the HS mice reset their response to hypoxia. Nonablative transplantation performed after cessation of host postnatal red blood cell amplification can be therapeutic long term for transfusion-dependent hemolytic anemias.

The role of mast cells in ischaemia-reperfusion injury in murine skeletal muscle.

To determine the role of mast cells in ischaemia-reperfusion (IR) injury to skeletal muscle, W(f)/W(f) mast cell-deficient and their corresponding wild-type mice were subjected to 70 min tourniquet ischaemia and 24 h reperfusion. As measured by nitroblue tetrazolium (NBT) staining, muscle viability was 9% in wild-type and 94% in mast cell-deficient animals (p<0.001). Assay of residual lactate dehydrogenase activity within the injured muscle (p<0.05) and histological examination confirmed the greater muscle necrosis in treated wild-type than in treated mast cell-deficient mice. There was no significant difference in the degree of neutrophil infiltration, tissue myeloperoxidase content or water content of IR-injured muscle in the two mouse phenotypes. To determine further the role of mast cells in IR injury, wild-type mice were treated 30 min prior to reperfusion with an intraperitoneal dose of either saline or the mast cell-stabilizing agent lodoxamide trometamol (2.5, 7.5, 25 or 75 mg/kg). Twenty-four hours after removal of the tourniquet, saline-treated gastrocnemius muscle had a mean viability of 14% compared with 28% (p<0.05) and 48% (p<0.01) after 25 mg/kg and 75 mg/kg of lodoxamide treatment, respectively. The ability of lodoxamide to stabilize mast cells was confirmed by histological examination. Ischaemic muscle reperfused for 1 h showed much less degranulation of mast cells in mice pretreated with lodoxamide (50 mg/kg) than in saline-treated controls. These findings suggest that mast cells are a major source of mediators of necrosis in IR injury to skeletal muscle.

Gene transfer to ankyrin-deficient bone marrow corrects spherocytosis in vitro.

OBJECTIVE: The goal of this study was to transfer by retroviral vector the cDNA for ankyrin to progenitors from normal bone marrow and from the nb/nb spherocytosis mutant deficient in expression of full-length ankyrin to achieve erythroid expression of functional ankyrin protein. MATERIALS AND METHODS: A minigene composed of the human ankyrin promoter, murine ankyrin cDNA, and the 3' human domain corresponding to the ankyrin 2.2 isoform was assembled in the retroviral vector, pG1. Murine erythroleukemia (MEL) cells, normal murine bone marrow cells, 3T3 fibroblasts, and nb/nb mutant bone marrow and spleen cells were transduced with the retroviral supernatant. Transduced mutant cells were induced to differentiate in liquid culture. Gene transfer was assessed by colony polymerase chain reaction (PCR) and reverse transcriptase (RT)-PCR, immunofluorescence, and Southern, Northern, and Western blot analysis. RESULTS: MEL cells, normal bone marrow progenitors, and nb/nb cells were all successfully transduced and expressed ankyrin by RT-PCR and Western blot. Transduced murine 3T3 fibroblasts and MEL cells exhibited cell membrane staining by immunofluorescence. Colony RT-PCR demonstrated dependence of expression on erythropoietin. In vitro, the transduced nb/nb cells matured to polychromatophils, whereas nontransduced nb/nb cells matured to microspherocytes. CONCLUSION: Retroviral transfer of ankyrin corrected the defect leading to formation of microspherocytes in erythroid differentiation cultures from the nb/nb mutant. The human ankyrin promoter conferred erythropoietin-dependent expression in normal and mutant erythroid progenitors, which could have implications for the gene therapy of human hemolytic anemias.