We studied the survival of 195 patients with agnogenic myeloid metaplasia (AMM) diagnosed between 1962 and 1992 in an attempt to stratify patients into risk groups. Median survival was 42 months. Adverse prognostic factors for survival were age > 60 years, hepatomegaly, weight loss, low hemoglobin level (Hb), low or very high leukocyte count (WBC), high percentage of circulating blasts, male sex, and low platelet count. A new scoring system based on two adverse prognostic factors, namely Hb < 10 g/dL and WBC < 4 or > 30 x 10(3)/L, was able to separate patients in three groups with low (0 factor), intermediate (1 factor), and high (2 factors) risks, associated with a median survival of 93, 26, and 13 months, respectively. An abnormal karyotype (32 cases of 94 tested patients) was associated with a short survival, especially in the low-risk group (median survival of 50 v 112 months in patients with normal karyotype). The prognostic factors for acute conversion were WBC > 30 x 10(3)/L and abnormal karyotype. Thus, hemoglobin level and leukocyte count provide a simple prognostic model for survival in AMM, and the adverse prognostic value of abnormal karyotype may be related to a higher rate of acute conversion.

The function of occludin (Occ) in the tight junction is undefined. To gain insight into its role in epithelial cell biology, occludin levels in Madin-Darby canine kidney II cells were suppressed by stably expressing short interfering RNA. Suppression of occludin was associated with a decrease in claudins-1 and -7 and an increase in claudins-3 and -4. Claudin-2 levels were unaffected. The tight junction "fence" function was not impaired in suppressed Occ (Occ-) clones, as determined by BODIPY-sphingomyelin diffusion in the membrane. The most striking changes were those related to control of the cytoskeleton and the "gate" function of tight junctions. A reduced ability of Occ- clones to extrude apoptotic cells from the monolayers suggested that neighbors of apoptotic cells either failed to sense their presence or were unable to coordinate cytoskeletal activity necessary for their extrusion. To further test the extent to which actin cytoskeletal activity depends on the presence of occludin, Occ- and Occ+ monolayers were depleted of cholesterol. Previous studies showed that cholesterol depletion is associated with reorganization of the actin cytoskeleton and a fall in transepithelial electrical resistance. In contrast to control Occ (Occ+) cells, transepithelial electrical resistance did not fall significantly in cholesterol-depleted Occ- monolayers and they failed to generate Rho-GTP, one of the signaling molecules involved in regulating the actin cytoskeleton. While steady-state transepithelial electrical resistance was similar in all clones, tight junction permeability to mono- and divalent inorganic cations was increased in Occ- monolayers. In addition, there was a disproportionately large increase in permeability to monovalent organic cations, up to 6.96 A in diameter. Chloride permeability was unaffected and there was little change in mannitol flux. The data suggest that occludin transduces external (apoptotic cells) and intramembrane (rapid cholesterol depletion) signals via a Rho signaling pathway that, in turn, elicits reorganization of the actin cytoskeleton. Impaired signaling in the absence of occludin may also alter the dynamic behavior of tight junction strands, as reflected by an increase in permeability to large organic cations; the permeability of ion pores formed of claudins, however, is less affected.

The authors retrospectively analyzed the initial characteristics, treatment, and clinical course in 147 patients with essential thrombocythemia (ET). Median age was 60 years and the M:F ratio was 0.69. At diagnosis, 53 patients were asymptomatic; 50 patients had functional symptoms (mainly vasomotor disturbances); 27 patients had large vessel thrombosis; 27 patients had a bleeding diathesis; and seven patients had both bleeding and thrombosis. The platelet count ranged from 0.7 to 2.92 X 10(12)/l. Forty-five of the 61 tested patients (61%) had prolonged bleeding time and/or platelet hypoaggregation. Three patients had in vitro spontaneous aggregation. No significant correlations were found between hemostatic findings and in vivo bleeding or thrombosis. The incidence of bleeding, however, was higher in patients with more than 2 x 10(12)/l platelets. Of 87 karyotypes performed with banding techniques, only four were abnormal. One hundred twenty-nine patients received one or more cytoreductive agents at diagnosis or during follow-up. Sixty patients received an antiaggregating agent. First-line therapy was radiophosphorus (32P) in 22 patients; busulfan in 35 patients; and hydroxyurea in 72 patients. Hydroxyurea required continuous maintenance therapy and had to be changed to another treatment in 12 of the initial responders because of inadequate control of thrombocythemia. During follow-up, 14 treated patients experienced one or several major thrombotic events. Two untreated patients also had major thrombosis. Only one major bleeding event was seen during follow-up. Median actuarial survival was 73.5% at 7 years and only one patient progressed to acute non-lymphocytic leukemia (ANLL). These results suggest that large vessel thrombosis is the main complication of ET. It appears largely unpredictable in a given patient at diagnosis but can be largely prevented by the control of thrombocythemia. Because of the low incidence of side effects of treatment in this experience, the authors believe that cytoreductive therapy is indicated in most patients with ET, as long as a group of patients with very low risk of thrombosis is not defined in prospective studies.

Airway smooth muscle (ASM) cells in culture stiffen when exposed to contractile agonists. Such cell stiffening may reflect activation of the contractile apparatus as well as polymerization of cytoskeletal biopolymers. Here we have assessed the relative contribution of these mechanisms in cultured ASM cells stimulated with serotonin (5-hydroxytryptamine; 5-HT) in the presence or absence of drugs that inhibit either myosin-based contraction or polymerization of filamentous (F) actin. Magnetic twisting cytometry was used to measure cell stiffness, and associated changes in structural organization of actin cytoskeleton were evaluated by confocal microscopy. We found that 5-HT increased cell stiffness in a dose-dependent fashion and also elicited rapid formation of F-actin as marked by increased intensity of FITC-phalloidin staining in these cells. A calmodulin antagonist (W-7), a myosin light chain kinase inhibitor (ML-7) and a myosin ATPase inhibitor (BDM) each ablated the stiffening response but not the F-actin polymerization induced by 5-HT. Agents that inhibited the formation of F-actin (cytochalasin D, latrunculin A, C3 exoenzyme, and Y-27632) attenuated both baseline stiffness and the extent of cell stiffening in response to 5-HT. Together, these data suggest that agonist-evoked stiffening of cultured ASM cells requires actin polymerization as well as myosin activation and that neither actin polymerization nor myosin activation by itself is sufficient to account for the cell stiffening response.

Like other tAMLs with a karyotype specific of de novo AML [balanced 11q23 rearrangement or t(15;17)], tAMLs with t(8;21), inv(16), or t(8;16) are usually characterized by a short latent period, previous treatment often combining a drug that directly reacts with DNA and an ATTop, and absence of preleukemic phase. Hematologic characteristics and response to treatment are also identical to those of de novo AML with the same karyotypes.