Chronic myelogenous leukemia simulating chronic granulomatous disease.

A 5-year illness of a child, characterized by recurrent bacterial infections and abnormal results of nitroblue tetrazolium dye reduction tests, was suggestive of chronic granulomatous disease but the illness terminated in overt myeloid leukemia. During this progression studies of leukocyte structure and metabolic activity revealed abnormalities that suggested the existence of a "preleukemic" state.     

Plasma exchange in the long-term management of Waldenstr?m's macroglobulinemia.

Two patients with Waldenström''s macroglobulinemia (WM), which had become resistant to cytotoxic drugs, were treated for features of the hyperviscosity syndrome by repeated plasma exchange with the continuous-flow blood-cell separator over periods of 36 and 28 months, respectively. After four initial weekly plasma exchanges the procedure was carried out every 4 to 6 weeks and both patients tolerated it well. Relative viscosity of the serum was maintained within the normal range in one patient, and both patients remained free of symptoms of the hyperviscosity syndrome. The results suggest that treatment of WM by long-term "maintenance" plasma exchange alone should be considered in any patient with complications due to chemotherapy or whose disease fails to respond to chemotherapy.     

A single mutation affects L-serine deaminase, L-leucyl-, L-phenylalanyl-tRNA protein transferase, and proline oxidase activity in Escherichia coli K-12.

A mutation at a single locus, wyb, results in several phenotypic changes in Escherichia coli K-12. The Wyb- phenotype includes: (i) an increase in L-serine deaminase activity, together with a loss of inducibility by L-leucine; (ii) an absence of L-leucyl-, L-phenylalanyl-tRNA protein transferase activity; (iii) inducibility of proline oxidase by proline; and (iv) a loss of ability to use maltose as a carbon and energy source.     

Chromosome replication during the division cycle in slowly growing, steady-state cultures of three Escherichia coli B/r strains.

The period of DNA synthesis C during the cell cycle was determined over a broad range of generation times in slowly growing, steady-state batch cultures in the exponential phase and in chemostat cultures of three strains of Escherichia coli, strains B/r A, B/r K, and B/r TT, utilizing measurements of average amounts of DNA per cell and cell survival after radioactive decay of 125I incorporated into the DNA of synthesizing cells. At each growth rate, values for cell survival and for C periods were the same within experimental errors for the three strains. The length of the DNA synthesis period increased linearly with generation (doubling) time T of the culture and approached a limiting value of C = 0.36T at very long generation times. In very slowly growing cultures, DNA replication was limited almost entirely to the final third of the cell cycle. D periods, between termination of DNA replication and cell division, were found to be relatively short at all growth rates for each strain. Average amounts of DNA per cell measured in slowly growing cultures of strains B/r A and B/r TT were indistinguishable from results for strain B/r K at the same growth rates. Amounts of DNA per cell calculated from the cell survival values alone are completely consistent with the measured DNA per cell.     

Comparison of the antilipolytic effect of metoprolol,acebutolol, and propranolol in man.

Metoprolol and acebutolol, two supposedly cardioselective beta-adrenoceptor antagonists, were tested in 11 healthy men against propranolol, a non-selective drug, for their effect on plasma free fatty acid concentrations before and after insulin. The fasting concentrations of free fatty acid were significantly reduced after acebutolol and propranolol, and their return to normal after insulin was delayed. Metoprolol had no significant effect on free fatty acid levels either before or after insulin. Although both selective and non-selective beta-blocking drugs should be expected to delay the return of free fatty acid values to normal after insulin, in contrast to propranolol and acebutolol, metoprolol had no such effect. This suggests that metoprolol may not be as effective as the other two drugs in controlling lipid metabolism during long-term treatment with beta-adrenoceptor antagonists.     

Lactose-proton symport by purified lac carrier protein

The lac carrier protein of Escherichia coli was purified by an improved procedure and its activity assayed by a rapid filter method. Following reconstitution of the carrier by octyl glucoside dilution, proteoliposomes were concentrated by filtration on a microporous filter. Lactose accumulation by adsorbed or entrapped proteoliposomes is driven by an artificially imposed pH gradient (interior alkaline), by a membrane potential (interior negative), or by a combination of both forces. Activity is almost completely abolished by the protonophore carbonyl cyanide m-chlorophenylhydrazone or by the competitive inhibitor thiodigalactoside. Addition of lactose to proteoliposomes under appropriate conditions results in alkalinization of the external medium. This effect is not observed with liposomes devoid of lac carrier or in the presence of proton conducting agents. The results provide a strong indication that the lac gamma gene product is the only protein in the cytoplasmic membrane of Escherichia coli required for lactose-proton symport.     

Lambda placMu insertions in genes of the leucine regulon: extension of the regulon to genes not regulated by leucine.

The leucine regulon coordinates the expression of several Escherichia coli genes according to the presence of exogenous leucine, which interacts with the lrp gene product, Lrp. We isolated and characterized 22 strains with lambda placMu insertions in Lrp-regulated genes. Lrp and leucine influenced gene expression in a surprising variety of ways. We identified two genes that are regulated by Lrp and not affected by L-leucine. We therefore rename this the leucine-lrp regulon. Genes coding for glycine cleavage and leucine biosynthesis enzymes have been identified as members of the leucine-lrp regulon. We suggest that the lrp gene product activates genes needed for growth in minimal medium, and we show that the gene is repressed by its own product and is highly repressed during growth in rich medium.     

Primary structure of the herpesvirus saimiri genome.

This report describes the complete nucleotide sequence of the genome of herpesvirus saimiri, the prototype of gammaherpesvirus subgroup 2 (rhadinoviruses). The unique low-G + C-content DNA region has 112,930 bp with an average base composition of 34.5% G + C and is flanked by about 35 noncoding high-G + C-content DNA repeats of 1,444 bp (70.8% G + C) in tandem orientation. We identified 76 major open reading frames and a set of seven U-RNA genes for a total of 83 potential genes. The genes are closely arranged, with only a few regions of sizable noncoding sequences. For 60 of the predicted proteins, homologous sequences are found in other herpesviruses. Genes conserved between herpesvirus saimiri and Epstein-Barr virus (gammaherpesvirus subgroup 1) show that their genomes are generally collinear, although conserved gene blocks are separated by unique genes that appear to determine the particular phenotype of these viruses. Several deduced protein sequences of herpesvirus saimiri without counterparts in most of the other sequenced herpesviruses exhibited significant homology with cellular proteins of known function. These include thymidylate synthase, dihydrofolate reductase, complement control proteins, the cell surface antigen CD59, cyclins, and G protein-coupled receptors. Searching for functional protein motifs revealed that the virus may encode a cytosine-specific methylase and a tyrosine-specific protein kinase. Several herpesvirus saimiri genes are potential candidates to cooperate with the gene for saimiri transformation-associated protein of subgroup A (STP-A) in T-lymphocyte growth stimulation.     

Dissection of Nodule Development by Supplementation of Rhizobium leguminosarum biovar phaseoli Purine Auxotrophs with 4-Aminoimidazole-5-Carboxamide Riboside

Purine auxotrophs of Rhizobium leguminosarum biovar phaseoli CFN42 elicit uninfected pseudonodules on bean (Phaseolus vulgaris L.). Addition of 4-aminoimidazole-5-carboxamide (AICA) riboside to the root medium during incubation of the plant with these mutants leads to enhanced nodule development, although nitrogenase activity is not detected. Nodules elicited in this manner had infection threads and anatomical features characteristic of normal nodules, such as peripheral vasculature rather than the central vasculature of the pseudonodules that were elicited without AICA riboside supplementation. Although 10⁵ to 10⁶ bacteria could be recovered from these nodules after full development, bacteria were not observed in the interior nodule cells. Instead, large cells with extensive internal membranes were present. Approximately 5% of the normal amount of leghemoglobin and 10% of the normal amount of uricase were detected in these nodules. To promote the development of true nodules rather than pseudonodules, AICA riboside was required no later than the second day through no more than the sixth day following inoculation. After this period, removal of AICA riboside from the root medium did not prevent the formation of true nodules. This observation suggests that there is a critical stage of infection, reached before nodule emergence, at which development becomes committed to forming a true nodule rather than a pseudonodule.