Expression of the neural cell adhesion molecule CD56 is associated with short remission duration and survival in acute myeloid leukemia with t(8;21)(q22;q22)

Although acute myeloid leukemia (AML) with t(8;21) (q22;q22) is associated with a high complete remission (CR) rate and prolonged disease-free survival, treatment outcome is not universally favorable. Identifying factors that predict for treatment outcome might allow therapy to be optimized based on risk. AML with t(8;21) has a distinctive immunophenotype, characterized by expression of the myeloid and stem cell antigens CD13, CD15, CD34, and HLADr, and frequent expression of the B-cell antigen CD19 and the neural cell adhesion molecule CD56, a natural killer cell/stem cell antigen. Because CD56 expression has been associated with both extramedullary leukemia and multidrug resistance, we sought to correlate CD56 expression with treatment outcome in AML with t(8;21). Pretreatment leukemia cells from 29 adult de novo AML patients with t(8;21) treated on Cancer and Leukemia Group B (CALGB) protocols were immunophenotyped by multiparameter flow cytometry as part of a prospective immunophenotyping study of adult AML (CALGB 8361). CD56 was expressed in 16 cases (55%). There was no correlation between CD56 expression and age, sex, white blood cell count, granulocyte count, the presence of additional cytogenetic abnormalities, or the presence of extramedullary disease at diagnosis. The CR rate to standard-dose cytarabine and daunorubicin was similar for cases with and without CD56 expression (88% v 92%; P = 1.0). Post-CR therapy included at least one course of high-dose cytarabine in 24 of 26 patients who achieved CR; numbers of courses administered were similar in cases with and without CD56 expression. Although post-CR therapy did not differ, CR duration was significantly shorter in cases with CD56 expression compared with those without (median, 8.7 months v not reached; P = .01), as was survival (median, 16.5 months v not reached; P = .008). We conclude that CD56 expression in AML with t(8;21) is associated with significantly shorter CR duration and survival. Our results suggest that CD56 expression may be useful in stratifying therapy for this subtype of AML.     

The sorghum photoperiod sensitivity gene, Ma3, encodes a phytochrome B

The Ma3 gene is one of six genes that regulate the photoperiodic sensitivity of flowering in sorghum (Sorghum bicolor [L.] Moench). The ma3R mutation of this gene causes a phenotype that is similar to plants that are known to lack phytochrome B, and ma3 sorghum lacks a 123-KD phytochrome that predominates in light-grown plants and that is present in non-ma3 plants. A population segregating for Ma3 and ma3 was created and used to identify two randomly amplified polymorphic DNA markers linked to Ma3. These two markers were cloned and mapped in a recombinant inbred population as restriction fragment length polymorphisms. cDNA clones of PHYA and PHYC were cloned and sequenced from a cDNA library prepared from green sorghum leaves. Using a genome-walking technique, a 7941-bp partial sequence of PHYB, was determined from genomic DNA from ma3 sorghum. PHYA, PHYB, and PHYC all mapped to the same linkage group. The Ma3-linked markers mapped with PHYB more than 121 centimorgans from PHYA and PHYC. A frameshift mutation resulting in a premature stop codon was found in the PHYB sequence from ma3 sorghum. Therefore, we conclude that the Ma3 locus in sorghum is a PHYB gene that encodes a 123-kD phytochrome.     

Export of importin alpha from the nucleus is mediated by a specific nuclear transport factor

NLS proteins are transported into the nucleus by the importin alpha/beta heterodimer. Importin alpha binds the NLS, while importin beta mediates translocation through the nuclear pore complex. After translocation, RanGTP, whose predicted concentration is high in the nucleus and low in the cytoplasm, binds importin beta and displaces importin alpha. Importin alpha must then be returned to the cytoplasm, leaving the NLS protein behind. Here, we report that the previously identified CAS protein mediates importin alpha re-export. CAS binds strongly to importin alpha only in the presence of RanGTP, forming an importin alpha/CAS/RanGTP complex. Importin alpha is released from this complex in the cytoplasm by the combined action of RanBP1 and RanGAP1. CAS binds preferentially to NLS-free importin alpha, explaining why import substrates stay in the nucleus.     

Chronic UVA (365-nm) irradiation induced scratching in hairless mice: dose-time dependency and the effect of ketanserin

In a study on the dose-response relationship for longwave UVA (UVA1; 340-400 nm) carcinogenesis in hairless mice scratch marks appeared after months of daily exposure as an unwanted side effect. Tumor induction in the highest of the 4 tested dose groups (receiving a daily dose of 430 kJ/m2 of 365-nm radiation) could not be determined because extensive scarification occurred prior to the development of any tumors. The induction of scratch marks could be scored and quantified in all 4 dose groups tested. The UVA1 dose-dependencies for the induction of tumors and scratch marks were compared. We found that the induction of scratch marks depended mainly on the cumulative UVA1 exposure, whereas tumor induction showed a lesser dose-dependency. An attempt was made to prevent the apparent pruritogenic effect of UVA1 irradiation and to understand its mechanism. The influence of ketanserin, a serotonin/histamine antagonist, on the UVA1 induction of scratch marks was tested in groups of 8 mice daily irradiated with 430 kJ/m2. No difference was found between treated and untreated animals. Histological examination of skin biopsies from irradiated mice from the 430-kJ/m2 dose group from the UVA1 carcinogenic experiment, showed no changes in numbers of mast cells or other inflammatory features when compared to skin biopsies from unirradiated control mice. This indicated that UVA1-induced scratching is not mediated through mast cell release of serotonin and/or histamine. An adequate therapeutic treatment which can prevent UVA1-induced scratching would enable us to test tumor induction with UVA1 over a larger dose range, and may provide additional insight in how this radiation damages the skin. It remains conjectural whether there exists an analogous UVA-induced pruritus in human skin.     

Iridoid glycoside biosynthesis in Penstemon secundiflorus. Another H-5, H-9 trans-iridoid glycoside

Isolation and characterization of the new iridoid 10-hydroxy-(5 alpha H)-6-epidihydrocornin from Penstemon secundiflorus (Scrophulariaceae) is described. In biosynthetic experiments, deoxyloganic acid was incorporated into the trans-fused iridoid glycosides (5 alpha H)-6-epidihydrocornin and 10-hydroxy-(5 alpha H)-6-epidihydrocornin in P. secundiflorus. Formation of the trans-fused compounds is therefore a late event in the biosynthesis and does not occur during iridoid formation by cyclization of the open chain monoterpene precursor. In the same plant, 8-epideoxyloganic acid was not incorporated into the trans-iridoids. Deoxyloganic acid was also incorporated into 10-hydroxyhastatoside (which bears an 8 beta-methyl group), while 8-epideoxyloganic acid was incorporated into penstemoside (with an 8 alpha-methyl group). Thus, iridoid biosynthetic pathways leading from both deoxyloganic acid and 8-epideoxyloganic acid were found in the same plant.     

Pharmacokinetic-pharmacodynamic relationships between pirarubicin exposure and hematotoxicity: clinical application using only one blood sample

This paper addresses the axial stiffness of human lumbar motion segments while subjected to moderate loads. Impacts in axial direction were applied to Functional Spinal Units while they were subjected to weights acting as static pre-load. Accelerations were recorded proximal and distal of the FSU. The transfer function and the resonant frequency were calculated from this data. The stiffness was calculated from the resonant frequency and the load. A simple non-linear model was fitted to the data and a linear relationship was found between stiffness squared and force. The non-linear component in the model strongly affected the stiffness within the chosen load range. The present model may allow in vivo dynamic force determination with improved accuracy, e.g. in experiments where accelerometers have been fixated to pins inserted into the spinous processes of lumbar vertebrae if the static force is known.     

Identification and characterization of heparin binding regions of the Fim2 subunit of Bordetella pertussis

Bordetella pertussis fimbriae bind to sulfated sugars such as heparin through the major subunit Fim2. The Fim2 subunit contains two regions, designated H1 and H2, which show sequence similarity with heparin binding regions of fibronectin, and the role of these regions in heparin binding was investigated with maltose binding protein (MBP)-Fim2 fusion proteins. Deletion derivatives of MBP-Fim2 showed that both regions are important for binding to heparin. The role of H2 in heparin binding was confirmed by site-directed mutagenesis in which basic amino acids were replaced by alanine. These studies revealed that Lys-186 and Lys-187 are important for heparin binding of MBP-Fim2, whereas Arg-179 is not required. Peptides derived from H1 and H2 (pepH1 and pepH2) also showed heparin binding activity. Using a series of peptides, in each of which a different basic amino acid was substituted for alanine, we demonstrated that the structural requirements for heparin binding differ significantly among pepH1 and pepH2 peptides. A Pepscan analysis of Fim2 revealed regions outside H1 and H2 which bind heparin and showed that not only basic amino acids but also tyrosines may be important for binding to sulfated sugars. A comparison of the heparin binding regions of Fim2 with homologous regions of Fim3 and FimX, two closely related but antigenically distinct fimbrial subunits, showed that basic amino acids and tyrosines are generally conserved. The major heparin binding regions identified in Fim2 are part of epitopes recognized by human antibodies, suggesting that the heparin binding regions are exposed at the fimbrial surface and are immunodominant. Since B. pertussis fimbriae show weak serological cross-reactivity, the differences in primary structure in the heparin binding regions of Fim2, Fim3, and FimX may affect antibody binding but not heparin binding, allowing the bacteria to evade antibody-mediated immunity by switching the fimbrial gene expressed.     

Multicomponent water proton transverse relaxation and T2-discriminated water diffusion in myelinated and nonmyelinated nerve

The influence of compartmental boundaries on water proton transverse relaxation and diffusion measurements was investigated in three distinct excised nerves, namely, the non-myelinated olfactory nerve, the Schwann cell myelinated trigeminal nerve, and the oligodendrocyte myelinated optic nerve of the garfish. The transverse relaxation decay curves were multiexponential and their decomposition yielded three primary components with T2 values approximately 30-50, 150, and 500 ms, which were subsequently assigned to water protons in the myelin, axoplasm, and interaxonal compartments. The short T2 component was absent in the non-myelinated olfactory nerve, but present in both myelinated nerves and thus provides supporting evidence for the use of quantitative T2 measurements to measure the degree of myelination. The signal contribution of each T2 component to the apparent diffusion coefficient measurements was varied by incrementing the spin-echo time with a preparatory CPMG train of radiofrequency pulses. The apparent diffusion coefficient and its anisotropy were shown to be independent of the spin-echo time over the range of 70 to 450 ms.     

Arteriolar reactivity in conscious diabetic rats: influence of aminoguanidine treatment

The effect of 6 weeks' streptozotocin (STZ)-induced (70 mg/kg) diabetes and aminoguanidine (AG) treatment (50 mg/kg s.c. or 250-750 mg/l given in drinking water) on arteriolar reactivity to vasoactive substances was investigated in conscious rats. Studies were performed in untreated control rats (n = 13), STZ-induced diabetic rats (n = 11), AG-treated control rats (n = 12), and AG-treated diabetic rats (n = 12). Rats were provided with a dorsal microcirculatory chamber that allowed intravital microscopy of striated muscle arterioles of varying diameter (A1, large; A2, intermediate; and A3, small arterioles) in conscious animals. The mean arterial pressure (MAP) and arteriolar diameter responses to intravenous infusion of the following drugs were examined: the endothelium-dependent vasodilator acetylcholine (ACh; 3, 10, and 30 microg x kg(-1) x min(-1)), the potassium-channel opener levcromakalim (LC; 30 microg/kg), and the vasoconstrictor agents ANG II (0.1 and 0.3 microg x kg(-1) x min(-1)) and norepinephrine (NE; 0.2, 0.6, and 2.0 microg x kg(-1) x min(-1)). Baseline MAP was lower in both diabetic groups versus the nondiabetic groups (P < 0.05). AG treatment had no influence on baseline MAP. The absolute change in MAP after drug infusion tended to be lower in the diabetic rats than in their nondiabetic littermates. Arteriolar vasodilatory responses to ACh and LC were attenuated in the diabetic animals (1 +/- 7 vs. 19 +/- 7% [P < 0.05] and 7 +/- 3 vs. 34 +/- 8% [P < 0.01] in A2, respectively). AG treatment of diabetic animals did not prevent the development of this disturbance. Vasoconstrictor responses were not influenced by the diabetic state. In the intermediate arterioles of AG-treated control rats, a hyperresponse was observed after ANG II infusion (-10 +/- 2 vs. -2 +/- 2%; P < 0.05) and a hyporesponse was observed after ACh and LC infusion (2 +/- 3 and 15 +/- 6%, respectively; P < 0.05 vs. untreated control rats). These data indicate that 6 weeks of experimental diabetes is associated with a decreased endothelium-dependent and -independent vasodilatation. AG treatment had no beneficial effect on this disturbance.