Diphtheria toxin fused to granulocyte-macrophage colony-stimulating factor eliminates acute myeloid leukemia cells with the potential to initiate leukemia in immunodeficient mice, but spares normal hemopoietic stem cells

We studied the cell kill induced by granulocyte-macrophage colony-stimulating factor (GM-CSF ) fused to Diphtheria Toxin (DT-GM-CSF ) in acute myeloid leukemia (AML) samples and in populations of normal primitive hemopoietic progenitor cells. AML samples from three patients were incubated in vitro with 100 ng/mL DT-GM-CSF for 48 hours, and AML cell kill was determined in a proliferation assay, a clonogenic assay colony-forming unit-AML (CFU-AML) and a quantitative long-term bone marrow (BM) culture ie, the leukemic-cobblestone area forming cell assay (L-CAFC). To measure an effect on cells with in vivo leukemia initiating potential DT-GM-CSF exposed AML cells were transplanted into immunodeficient mice. In two out of three samples it was shown that all AML subsets, including those with long-term abilities in vivo (severe combined immunodeficient mice) and in vitro (L-CAFC assay) were reduced in number by DT-GM-CSF. Cell kill induced by DT-GM-CSF could be prevented by coincubation with an excess of GM-CSF, demonstrating that sensitivity to DT-GM-CSF is specifically mediated by the GM-CSF receptor. Therefore, binding and internalization of GM-CSF probably occur in immature AML precursors of these two cases of AML. The third AML sample was not responsive to either GM-CSF or DT-GM-CSF. The number of committed progenitors of normal bone marrow (burst-forming unit-erythroid, colony-forming unit granulocyte- macrophage, and cobble stone area forming cell [CAFC] week 2) and also the number of cells with long-term repopulating ability, assayed as week 6 CAFC, were unchanged after exposure to DT-GM-CSF (100 ng/mL, 48 hours). These studies show that DT-GM-CSF may be used to eliminate myeloid leukemic cells with long-term potential in vitro and in immunodeficient mice, whereas normal hemopoietic stem cells are spared.     

Ultrasound evaluation of piglet diaphragm function before and after fatigue

Clinically, a noninvasive measure of diaphragm function is needed. The purpose of this study is to determine whether ultrasonography can be used to 1) quantify diaphragm function and 2) identify fatigue in a piglet model. Five piglets were anesthetized with pentobarbital sodium and halothane and studied during the following conditions: 1) baseline (spontaneous breathing); 2) baseline + CO2 [inhaled CO2 to increase arterial PCO2 to 50-60 Torr (6.6-8 kPa)]; 3) fatigue + CO2 (fatigue induced with 30 min of phrenic nerve pacing); and 4) recovery + CO2 (recovery after 1 h of mechanical ventilation). Ultrasound measurements of the posterior diaphragm were made (inspiratory mean velocity) in the transverse plane. Images were obtained from the midline, just inferior to the xiphoid process, and perpendicular to the abdomen. M-mode measures were made of the right posterior hemidiaphragm in the plane just lateral to the inferior vena cava. Abdominal and esophageal pressures were measured and transdiaphragmatic pressure (Pdi) was calculated during spontaneous (Sp) and paced (Pace) breaths. Arterial blood gases were also measured. Pdi(Sp) and Pdi(Pace) during baseline + CO2 were 8 +/- 0.7 and 49 +/- 11 cmH2O, respectively, and decreased to 6 +/- 1.0 and 27 +/- 7 cmH2O, respectively, during fatigue + CO2. Mean inspiratory velocity also decreased from 13 +/- 2 to 8 +/- 1 cm/s during these conditions. All variables returned to baseline during recovery + CO2. Ultrasonography can be used to quantify diaphragm function and identify piglet diaphragm fatigue.     

Revision of the Scheme for Extraction and Classification of Dyes from Polyacrylonitrile Fibres

The simple sequential scheme for the extraction and classification of dyes from 1–2–cm lengths of polyacrylonitrile fibres reported by Beattie et al., J. S. D. C, 95 (1979) 295, is revised to avoid misclassification of some basic dyes.     

EPR kinetic studies of oxygen release in thylakoids and PSII membranes: a kinetic intermediate in the S3 to S0 transition

Time-resolved EPR oximetry has been used to determine the oxygen release kinetics in spinach thylakoids and PSII membranes. We observe release kinetics with half-times of approximately 0.85 and approximately 1.45 ms for thylakoids and PSII membranes, respectively, which are in close agreement with the EPR determined Yz decay kinetics for the S3 --> --> S0 transition in these systems. The results show conclusively that water-oxygen chemistry is not a rate-limiting step in the donor side of PSII under normal turnover conditions. By analyzing the oxygen release kinetics in thylakoids under nonphysiological, but still functionally competent conditions (low pH or high salt), we observed an initial delay in the O2 release of up to 200 microseconds following flash turnover from the S3 state. This is the first direct indication of a probable quasi-stable intermediate in the S3 --> --> S0 turnover of PSII, possibly representing the putative S4 state. Under conditions more closely approaching physiological, no such delay was resolved, indicating that the S4 --> O2 transition occurs within 50 microseconds under such circumstances. Two possible reaction sequences for O2 formation consistent with these and other data are discussed. It is suggested that the more probable form of "S4" is in fact the S3 + Yz* combination, which must undergo some molecular rearrangement on the tens to hundreds of microseconds time scale before O2 formation chemistry occurs.     

The cataract extraction-refraction-implantation technique for IOL power calculation in difficult cases

We present an unusual case of polydactyly of the thumb. The patient, despite having a fully developed nail bed, had a duplication at the metacarpophalangeal level consisting of a single bony phalanx. The Wassel classification of polydactyly, which is the most commonly cited classification scheme, does not include this particular anomaly. In addition, there has been no reference to this type of polydactyly in the literature.