Gene order, amplification, and rearrangement of chromosome band 11q23 in hematologic malignancies

Eleven genes were found to be amplified in a patient with acute myelogenous leukemia and a homogeneous staining region 11q23qter. The gene order of such region was determined by using transverse alternating field electrophoresis of normal cell DNA and Southern blots of DNA from somatic cell hybrids, each containing a single human derivative chromosome 11 from six different chromosomal defects. This in turn allowed us to uncover a breakpoint in band 11q23.3 between the CD3 gamma and the ets-1 genes in genomic rearrangements found in acute myelogenous leukemia, acute lymphocytic leukemia, and B-cell diffuse lymphoma. The breakpoint of a constitutional deletion from a patient whose mother and brother have a heritable 11q23.3 fragile site occurs in the same region.

Stimulation of IS1 excision by bacteriophage P1 ref function

Lysogenization by a c1ts variant of coliphage P1, P1c1.100, markedly increased the frequency of reversion of a galT::IS1 mutation. The formation of Gal+ colonies presumably occurs by microhomologous recombination between the 9-base-pair repeats in galT (CGCCGCTAC) generated by the transposition of IS1. The responsible P1 gene, ref, has been cloned and sequenced. ref encodes a 22.8-kilodalton protein and is located near the P1 site-specific recombination function, cre. Expression of ref was repressed by P1 c+. The absence of a distinctive ribosome-binding site is consistent with a poor translation of ref from an expression vector in vivo. Placement of a ribosome-binding site before ref resulted in the extensive synthesis of the Ref protein. Ref stimulated precise excision in recB or himA cells, but not in recA mutants. Ref was active in lexA3 mutants, suggesting that the recombination activity of RecA was directly involved in the reaction. We have constructed a P1c1.100 ref::Tn10 mutant. The absence of Ref did not appear to restrict dramatically the ability of P1 to grow lytically or to form lysogens. Thus, the role of ref in the physiology of P1 remains to be determined.

A technique for double resonant operation of birdcage imaging coils

The type of radio-frequency (RF) coil known as a high-pass birdcage consists of a set of N; wires arranged axially on the surface of a cylinder and connected by capacitors at each end. Such coils are widely used for NMR imaging because of the high degree of field homogeneity they provide. It is shown how to create homogeneous fields at two frequencies, using an unequal distribution of capacitance. A theoretical analysis which uses the discrete Fourier transform of the currents with respect to the angular positions of the N; wires is presented. A perturbation theory analysis indicates a small sacrifice in homogeneity. The root-mean-square deviation of field magnitude around a circle is proposed as a measure of field inhomogeneity. For the case of double resonance at proton and fluorine frequencies, the loss of homogeneity is at worst 1% and is small compared to the natural inhomogeneity for an N=8 wire coil for radii up to one half the coil radius. The presence of a conducting shield degrades the homogeneity. The theoretical ideas were confirmed in a computer simulation of one particular coil design. A working coil was constructed and images obtained of proton and fluorine phantoms.

Retrieval of stratospheric background aerosol scattering coefficient from twilight polarization measurements

A backward Monte Carlo computation procedure has been used to simulate the intensity and degree of polarization of the twilight sky during 1977. It was found that the single scattering approximation is applicable for detection of stratospheric aerosols by twilight measurement during background periods. Based on the simulation, a scheme is proposed for retrieving the stratospheric aerosol scattering coefficient utilizing the measured degree of polarization at the 0.7-microm wavelength in the zenith direction of the twilight sky. Compared with the in situ measurement, both the retrieved total optical depth and the retrieved profile of the aerosol scattering coefficient below 30 km agree reasonably well with measurements.

A possible synergism of dietary phosphate and urine-acidifying salts in preventing silica urolithiasis in a rat model

Using an animal model involving rats fed tetraethylorthosilicate, the minimal effective dietary concentration of ammonium chloride for reduction of silica urolithiasis was determined to be approximately 0.10 equivalents/kg diet. Ammonium sulfate appeared to be only slightly less effective. The lower incidences of urolithiasis were associated with urinary pH less than 7. A subprophylactic concentration (0.067 equivalents/kg diet) of ammonium chloride was factored with three levels of supplemental phosphorus (0, 0.15 and 0.30%) from Na2HPO4 to determine whether the antiurolithic effects of dietary phosphate and urinary-acidifying salts are synergistic. Phosphate had no effect on urinary pH. A 50% urolith incidence occurred in controls; the incidence was 25% (P = 0.08) with 0.15 and 10% (P less than 0.01) with 0.30% phosphorus. Urinary pH was 7.5 in controls compared with approximately 7.2 in rats given the subprophylactic level of ammonium chloride, but ammonium chloride alone had no effect on urolithiasis. However, complete protection from urolithiasis was provided by each of the two levels of phosphorus in combination with ammonium chloride. It is concluded that supplemental dietary phosphorus is most effective for protection against silica urolithiasis under conditions contributing toward urinary acidification due to a possible synergism between dietary phosphorus and urinary acidifying salts.

The effect of hypotension on brain energy state during prolonged neonatal seizure

Prolonged seizures in the human neonate may be complicated by systemic hypotension. To examine the effect of systemic hypotension on brain metabolic state during seizure, neonatal dogs were made hypotensive (by exsanguination) during bicuculline-induced seizure. Measurement of regional cerebral blood flow showed that moderate hypotension did not impair cerebral perfusion during seizure. Measurement of brain energy state with in vivo 31P nuclear magnetic resonance spectroscopy disclosed a similar pattern of alteration of high energy phosphates in animals subjected to seizure or to the combination of seizure and hypotension. The additional metabolic stress imposed by moderate hypotension during seizure in the neonatal dog appears to be slight.

Beta adrenergic control of extrarenal potassium disposal. A beta-2 mediated phenomenon

Beta adrenergic control of extrarenal potassium disposal was evaluated by examining the effects of physiologic doses of beta adrenergic agonists and antagonists on potassium tolerance in acutely nephrectomized rats. Following an acute intravenous potassium load (0.17 mEq/100 g over 60 min), the plasma potassium concentration rose significantly less in animals concomitantly treated with epinephrine at a dose that raises plasma epinephrine concentration to levels found during surgical stress (maximum plasma K 2.2 vs. 2.9 mEq/1 in controls receiving KCl alone; p less than 0.005). Similar results were observed with the selective beta-2 agonists salbutamol and terbutaline. Conversely, the rise in plasma potassium concentration was significantly greater in rats treated with low-dose propranolol (beta-1 + beta-2 blockade) and with butoxamine (beta-2 blockade) compared to control animals. In contrast, the selective beta-1 blocking agent metoprolol had no effect on potassium tolerance. Alterations in potassium tolerance following the administration of various beta adrenergic agonists and antagonists could not be explained by changes in plasma insulin, renin, or glucose concentration or by differences in the acid-base or hemodynamic status of the animals. The data suggest that beta adrenergic control of extrarenal potassium disposal occurs with physiologic stimulation or blockade of the beta-2 receptor site.

The transposition properties of Tn2 in E. coli

We report the characterization of Tn2 transpositions into the chromosome and into an F' lacproB episome of E. coli. When Tn2 transposes into the chromosome a proportion of the insertions result in auxotrophy. These insertions can revert to prototrophs and lose ampicillin resistance concomitantly. However, Tn2 insertions in F' lacproB are often associated with deletions, and it seems probable that insertion and deletion occur simultaneously.

Conformational transitions of polypeptides in ternary solvent systems

Phase diagrams for conformational transitions of polypeptides in ternary organic solvent systems containing two active and one inert component are calculated for a model which takes into account possible interaction of the two active components with each other as well as with the polypeptide backbone. The results of experimental determinations of conformational transitions and isothermal phase boundaries for poly(beta-benzyl L-asparate) (PBA) in three-model solvent systems are in generally good accord with the theory. The solvent systems are: (a) 1-chloropropionic acid-dichloroacetic acid (DCA)-1,1,2,2-tetrachloroethane (TCE), (b) monochloroacetic acid-DCA-TCE, and (c) dimethyl sulfoxide-DCA-TCE.