Cardiotoxin-induced skeletal muscle injury elicits profound changes in anabolic and stress signaling,and muscle fiber type composition

To improve muscle healing upon injury, it is of importance to understand the interplay of key signaling pathways during muscle regeneration. To study this, mice were injected with cardiotoxin (CTX) or PBS in the Tibialis Anterior muscle and were sacrificed 2, 5 and 12 days upon injection. The time points represent different phases of the regeneration process, i.e. destruction, repair and remodeling, respectively. Two days upon CTX-injection, p-mTORC1 signaling and stress markers such as BiP and p-ERK1/2 were upregulated. Phospho-ERK1/2 and p-mTORC1 peaked at d5, while BiP expression decreased towards PBS levels. Phospho-FOXO decreased 2 and 5 days following CTX-injection, indicative of an increase in catabolic signaling. Furthermore, CTX-injection induced a shift in the fiber type composition, characterized by an initial loss in type IIa fibers at d2 and at d5. At d5, new type IIb fibers appeared, whereas type IIa fibers were recovered at d12. To conclude, CTX-injection severely affected key modulators of muscle metabolism and histology. These data provide useful information for the development of strategies that aim to improve muscle molecular signaling and thereby recovery.

     

Clinical features, outcome, and meningococcal genotype in 258 adults with meningococcal meningitis: a prospective cohort study

Meningococcal meningitis remains a life-threatening disease. Neisseria meningitidis is the leading cause of meningitis and septicemia in young adults and is a major cause of endemic bacterial meningitis worldwide. The Meningitis Cohort Study was a Dutch nationwide prospective observational cohort study of adults with community-acquired bacterial meningitis, confirmed by culture of cerebrospinal fluid, from October 1998 to April 2002. Patients underwent a neurologic examination at discharge, and outcome was graded with the Glasgow Outcome Scale. Serogrouping, multi-locus sequence typing, and susceptibility testing of meningococcal isolates were performed.The study identified 258 episodes of meningococcal meningitis in 258 patients. The prevalence of the classical triad of fever, neck stiffness, and change in mental status was low (70/258, 27%). When rash was added to the classical triad, 229 of 258 (89%) patients had at least 2 of 4 signs. Systolic hypotension was associated with rash (22/23 vs. 137/222, p = 0.002) and absence of neck stiffness (6/23 vs. 21/220, p = 0.05). Neuroimaging before lumbar puncture was an important cause of delay of therapy: antibiotics were not initiated before computed tomography (CT) scan in 85% of patients who underwent CT scan before lumbar puncture. Unfavorable outcome occurred in 30 of 258 (12%) patients, including a mortality rate of 7%. Neurologic sequelae occurred in 28 of 238 (12%) patients, particularly hearing loss (8%). Factors associated with sepsis and infection with meningococci of clonal complex 11 (cc11) are related with unfavorable outcome.     

Allogeneic bone marrow transplantation after high-dose busulfan and cyclophosphamide in patients with acute nonlymphocytic leukemia

Ninety-nine patients with acute nonlymphocytic leukemia (ANLL) received HLA-identical bone marrow transplants (BMTs) from sibling donors after preparation with high doses of busulfan and cyclophosphamide. Forty- nine patients were transplanted in first complete remission (CR), and 50 patients were transplanted in second and third CR and early relapse. Fifty-three received one of three regimens containing primarily low- dose cyclophosphamide (group I) for graft-v-host disease (GVHD) prophylaxis; since March 1983, 46 patients received intravenous (IV) cyclosporine (group II). After December 1983, only cytomegalovirus (CMV)-seronegative blood products were used in appropriate patients, and since April 1984 patients seropositive for herpes-simplex virus (HSV) and CMV received high-dose acyclovir prophylaxis. For patients transplanted in first CR, there was a significantly lower incidence of acute GVHD (P = .005) and deaths related to GVHD and interstitial pneumonitis (P = .001) in patients in group II. This was reflected in an improved Kaplan-Meier probability of disease-free survival (DFS) in the 22 patients transplanted in group II as compared with the 27 patients in group I (64% +/- 10% v 30% +/- 9%, P = .017). The probability of remaining in remission was slightly lower in group II (82% +/- 9% v 94% +/- 6%, P = .479). For patients transplanted in second and third CR and early relapse, the incidence of acute GVHD (P = .026) and deaths related to GVHD and interstitial pneumonitis was significantly lower in group II (P = .029); the probability of remaining in remission was also less (47% +/- 15% v 91% +/- 15%, P = .022). However, the probability of DFS was not significantly different between the two groups (26% +/- 10% v 35% +/- 18%, P = .957). We conclude that transplantation for patients in first CR who received IV cyclosporine therapy is effective treatment; patients with more refractory disease treated with the same cyclosporine regimen (group II) had a lower incidence of GVHD than those treated in group I, but survival did not improve because of an increase in the number of relapses and other nonleukemic complications.     

Elongator is a histone H3 and H4 acetyltransferase important for normal histone acetylation levels in vivo

The elongating, hyperphosphorylated form of RNA polymerase II is associated with the Elongator complex, which has the histone acetyltransferase (HAT) Elp3 as a subunit. Here we show that, in contrast to the isolated Elp3 subunit, the activity of intact Elongator complex is directed specifically toward the amino-terminal tails of histone H3 and H4, and that Elongator can acetylate both core histones and nucleosomal substrates. The predominant acetylation sites are lysine-14 of histone H3 and lysine-8 of histone H4. The three smallest Elongator subunits--Elp4, Elp5, and Elp6--are required for HAT activity, and Elongator binds to both naked and nucleosomal DNA. By using chromatin immunoprecipitation, we show that the levels of multiply acetylated histone H3 and H4 in chromatin are decreased in vivo in yeast cells lacking ELP3.     

Naturally occurring anticoagulants and bone marrow transplantation: plasma protein C predicts the development of venocclusive disease of the liver

Venocclusive disease (VOD) of the liver is the major dose-limiting complication of pretransplant regimens for bone marrow transplantation. Recent reports from different groups point to the involvement of the hemostatic mechanism in the development of VOD. We measured the naturally occurring anticoagulants protein C, antithrombin III, and protein S in 45 patients undergoing bone marrow transplantation for hematologic malignancies before cytoreductive therapy and after transplant. The aim of this prospective study was both to evaluate the status of the naturally occurring anticoagulant pathway in patients who develop VOD compared with patients who do not, and to find a predictive marker of VOD. In transplant patients, protein C decreased from before cytoreductive therapy to posttransplant, whereas protein S and antithrombin III did not. In a multivariate analysis, protein C was the only variable that could independently discriminate between VOD and non- VOD patients at all times. Discriminant function analysis established that low protein C levels before cytoreductive therapy predicted the occurrence of VOD with good sensitivity and specificity.     

Cytochemical, cytogenetic, immunophenotypic and tumorigenic characterization of two hairy cell lines

Two cell lines (EH and HK) were derived from two patients with hairy cell leukemia (HCL). Both patients exhibited a clinical picture characteristic of HCL, including splenomegaly, cytopenias, and tartrate- resistant acid phosphatase (TRAP)-positive "hairy" lymphocytes in blood and marrow. EH and HK were demonstrably of B lineage, as judged by cytochemistry and immunophenotype, including expression of B1, B2, and LEU-12 antigens and of monoclonal surface immunoglobulins (slgs). Monoclonality was confirmed by clonal karyotype abnormality demonstrated in cell line HK. HCL parentage suggested by cytochemistry and electron microscopy was confirmed by the immunophenotypic observation that HCL lines expressed antigens alpha S-HCL1, alpha S- HCL3, and cCLLa. While alpha S-HCL1 and alpha S-HCL3 are nonspecific, their co-expression is characteristic of HCL cells. The cCLLa is a novel 69-kd membrane HCL-associated polypeptide antigen not shared by circulating normal T or B lymphocytes nor by malignant cells from unrelated lymphoid or nonlymphoid malignancies. The doubling time of EH and HK was 24 and 36 hours, respectively. While HK included a small subset of Epstein-Barr virus (EBV) nuclear antigen-positive cells, EH cells were homogeneously negative for the presence of this antigen. Both cell lines were consistently implantable in irradiation- preconditioned immunodeficient mice giving rise to primary tumors and widespread metastasis.     

Selectin-mediated rolling of neutrophils on immobilized platelets

Interaction between neutrophils and platelets at the site of vascular damage or in ischaemic tissue may promote thrombosis and/or vascular occlusion. To study this interaction, we have developed a novel technique that allows visualization of adhesion of flowing neutrophils to immobilized, activated platelets. The total number of adherent neutrophils decreased with increasing wall shear stress in the range 0.05 to 0.4 Pa. Although a proportion of the adherent neutrophils were stationary, most were rolling with a velocity greater than 0.4 micron/s. The percentage of rolling cells increased with increasing wall shear stress, but the mean rolling cell velocity was nearly independent of shear stress. Adhesion of neutrophils was nearly abolished by treatment of the platelets with antibody to P-selectin, or by treatment of neutrophils with either neuraminidase, dextran sulfate, or EDTA. Studies with a series of antibodies to L-selectin (TQ-1, Dreg- 56, LAM1-3, and LAM1-10) suggested that this molecule was one neutrophil ligand for rolling adhesion. Thus, sialylated carbohydrate on neutrophils appears essential for P-selectin-mediated adhesion, and a proportion of this ligand may be presented by L-selectin. Treatment of the neutrophils with N-formyl-methionyl-leucyl-phenylalanine decreased the number of rolling cells, and increased the rolling velocity, possibly due to shedding of neutrophil ligand(s) and/or cell shape change. In vivo, immobilized platelets could play an important role in promoting attachment of neutrophils to vessel walls, eg, by slowing neutrophils so that integrin-mediated immobilization could occur.