Aluminium inhibits muscarinic agonist-induced inositol 1,4,5-trisphosphate production and calcium mobilization in permeabilized SH-SY5Y human neuroblastoma cells

The effects of aluminium (as Al3+) on carbachol-induced inositol 1,4,5-trisphosphate (InsP3) production and Ca2+ mobilisation were assessed in electropermeabilised human SH-SY5Y neuroblastoma cells. Al3+ had no effect on InsP3-induced Ca2+ release but appreciably reduced carbachol-induced Ca2+ release (IC50 of approximately 90 microM). Al3+ also inhibited InsP3 production (IC50 of approximately 15 microM). Dimethyl hydroxypyridin-4-one, a potent Al3+ chelator (Ks = 31), at 100 microM was able to abort and reverse the effects of Al3+ on both Ca2+ release and InsP3 production. These data suggest that, in permeabilised cells, the effect of Al3+ on the phosphoinositide-mediated signalling pathway is at the level of phosphatidylinositol 4,5-bisphosphate hydrolysis. This may reflect interference with receptor-G protein-phospholipase C coupling or an interaction with phosphatidylinositol 4,5-bisphosphate.

The production and preclinical characterization of a chimeric anti-breast-cancer antibody, cBC2

A chimeric (mouse-human) BC2 antibody (cBC2) was produced which may be used in the diagnosis and treatment of breast cancer. The BC2 variable region genes were amplified by polymerase chain reaction (PCR), using oligonucleotide primers homologous to the framework sequences of mouse VH and V kappa genes. The PCR products were used to create cBC2 expression vectors containing the mouse BC2 VH and V kappa and human constant region (IgG1 and K) genes. Chimeric antibody was produced following transfection of these constructs into Sp2/0 myeloma cells. Binding assays in vitro demonstrated that cBC2 had the same specificity for human milk fat globule membrane (HMFGM) and MUC1+ cells as mBC2, and bound antigen with a similar affinity (cBC2, Ka 5.53 +/- 2.09 x 10(8); mBC2, Ka 1.44 +/- 0.98 x 10(9)). Functionally, only cBC2 (5-25 micrograms ml-1), was able to mediate antibody-dependent cellular cytotoxicity (ADCC) with human effector cells, with 25% maximal specific lysis of MUC1+ cells at an E/T ratio of 100:1. Human complement-mediated lysis was minimal (10-15% specific lysis) with both mBC2 and cBC2. Neither cBC2 nor mBC2 was able to inhibit tumour growth in vivo in the absence of covalently coupled anticancer drugs. However, biodistribution studies demonstrated that both antibodies preferentially targeted MUC1+ tumour cells, with 17% of the injected dose of cBC2, as compared to 27% of mBC2, localized to the MUC1+ tumour at 24 h (less than 6% detected in any other tissue).

Solubilities and solvation of aluminum(III), iron(III), and indium(III) 8-hydroxyquinolinates in methanol/water mixtures

Solubilities are reported for aluminum, indium, and iron(III) complexes of 8-hydroxyquinoline and its 5-nitro, 5-sulfonato, and 7-iodo-5-sulfonato derivatives in water, methanol, and water/methanol mixtures, at 298.2 K. Transfer chemical potentials for the respective complexes have been derived from these data, and their trends are discussed in terms of solvation of the complexes by water and methanol.

The clinical usefulness of the platelet aggregation test for the diagnosis of heparin-induced thrombocytopenia

The platelet aggregation test is widely used for the diagnosis of heparin-induced thrombocytopenia (HIT), a potentially serious complication of heparin therapy. We have evaluated its sensitivity and specificity in comparison with those of the 14C-serotonin release test. The sensitivity of the platelet aggregation test was found to vary with the heparin concentration and the donor of the platelets used in the test. The optimal heparin concentrations were between 0.1 and 1.0 U/ml. Using these heparin concentrations, the mean sensitivity varied from 39% (with the least reactive platelets) to 81% (with the most reactive platelets). In comparison, the sensitivity of the release test ranged from 65% to 94%. The specificities of the platelet aggregation test were 82%, 90% and 100% for the following control groups: (1) non-thrombocytopenic patients given heparin, (2) patients with thrombocytopenia due to other causes, and (3) normal controls not given heparin, respectively. The corresponding specificities for the release test was 94%, 90% and 100%. The specificities can be further increased to 100% for all controls with the adoption of a two-point system which defines a positive result as one in which platelet aggregation occurs with a low heparin concentration (0.5 U/ml) but not with 100 U heparin/ml. For optimal results, a two-point platelet aggregation test should be performed with heparin concentrations of 0.5 and 100 U/ml and using platelets of more reactive donors.

Plasma amino acids in patients with acute nonlymphocytic leukemia receiving parenteral nutrition

OBJECTIVE

To assess the effect of parenteral amino acid solutions on plasma amino acid concentrations in patients with acute nonlymphocytic leukemia (ANLL) receiving parenteral nutrition (PN).

DESIGN

Ten patients were studied at diagnosis, on the morning PN was started, and three times during PN therapy coinciding with the sequential administration of three different amino acid solutions (Aminosyn, FreAmine HBC, and TrophAmine). The order of amino acid solution administration in each patient was by a randomized, block design.

RESULTS

The patients were undergoing identical intensive induction therapy. There was no significant difference in the number of days they received PN or the amount of protein or calories received during the three PN study periods. At diagnosis, phenylalanine and glutamic acid concentrations were elevated compared with previously published normal values and remained elevated at all observation times. During PN, asparagine, aspartic acid, and tyrosine concentrations were significantly lower with all three amino acid solutions compared with their concentrations at diagnosis. Glycine and threonine concentrations were also significantly lower with FreAmine HBC and TrophAmine administration and cysteine concentrations were significantly lower with FreAmine HBC administration than at the time of diagnosis. Aminosyn was associated with plasma amino acid concentrations most similar to those measured at diagnosis.

CONCLUSIONS

These results indicate that most amino acid concentrations fall within the normal range at diagnosis in the ANLL patients studied. Plasma concentrations for certain amino acids can be influenced by the amino acid solution used in PN. Further understanding of the derangements in amino acid metabolism and the influence of parenterally administered amino acid solutions on plasma amino acid concentrations may lead to improvements in the nutritional support of cancer patients.

Immunomagnetic positive selection and colony culture of CD34+ cells from blood

Immunomagnetic separation has been used to enrich CD34-positive cells in umbilical cord blood. Cell purities were increased from 0.59% preseparation to 92.7% postseparation (n = 16) with a mean yield of 75.7%. CFU were enriched 127 fold by immunomagnetic separation. Addition of combinations of recombinant growth factors resulted in cloning efficiencies of greater than 50%.

Tensile bond strengths of three chemical and one electrolytic etching systems for a base metal alloy

This study compared the tensile bond strength of Rexillium III disks etched by three chemical etching systems and the electrochemical etching technique. Cast Rexillium III disks were etched by the following etching systems: electrochemical, Assure-Etch, Met-Etch gel, and Etch-It gel. Thermocycled samples were loaded to failure in tension on an Instron testing machine using a crosshead speed of 5 mm/minute. Samples etched electrochemically yielded significantly greater bond strengths than those etched chemically (p less than 0.05). The rank of the groups was: Electrochemical greater than Assure-Etch = Met-Etch greater than Etch-It. Scanning electron micrograph evaluations of the etching patterns supported the bond strength determinations.

Torsional testing of Canal Master U hand instruments

Ten each of size 25, 30, 35, 40, and 45 Canal Master U hand instruments were tested for torsional failure and revolutions to failure. In addition, the point at which separation occurred was measured on the instrument shaft. An Instron 1125 machine was used for all torsion testing. The mean torque failure value for size 25 and 35 Canal Master U instruments exceeded the ADA specification No. 28 minimum values while sizes 30, 40, and 45 were below the ADA minimum average values. All Canal Master U averages for revolutions to failure exceeded the ADA minimums. Although size 25 was above the minimum average, due to a wide range of values, 5 of the 10 were below the ADA specification No. 28 values. The point of instrument separation was 0.325 to 1.575 mm behind the cutting head. Due to the structural design differences of endodontic files versus Canal Master U, it is suggested that an additional category of ADA specification be introduced for Canal Master endodontic instruments.