Isolation of pathogens other than Yersinia pestis during plague investigations.

From 1975 to 1978, 37 isolates of Pasteurella multocida, 1 of Salmonella enteriditis, and 5 of Francisella tularensis were recovered from 42 mammalian specimens and 1 flea pool submitted for examination for evidence of infection with Yersinia pestis. Most of the specimens were collected during investigations of either a human plague infection or a reported epizootic among rodent populations. All specimens were of species regularly or occasionally involved in plague or tularemia cycles in nature and most were collected in areas of known plague or tularemia activity.     

Identification, isolation, and characterization of the structural gene encoding the delta' subunit of Escherichia coli DNA polymerase III holoenzyme.

The gene encoding the delta' subunit of DNA polymerase III holoenzyme, designated holB, was cloned by a strategy in which peptide sequence was used to derive a DNA hybridization probe. The gene maps to 24.95 centisomes of the chromosome. Sequencing of holB revealed a 1,002-bp open reading frame predicted to produce a 36,936-Da protein. The gene has a ribosome-binding site and promoter that are highly similar to the consensus sequences and is flanked by two potential open reading frames. Protein sequence analysis of delta' revealed a high degree of similarity to the dnaX gene products of Escherichia coli and Bacillus subtilis, including one stretch of 10 identical amino acid residues. A lesser degree of similarity to the gene 44 protein of bacteriophage T4 and the 40-kDa protein of the A1 complex (replication factor C) of HeLa cells was seen. The gene, when placed into a tac promoter-based expression plasmid, directed expression of two proteins of similar size. By immunodetection with anti-holoenzyme immunoglobulin G, both proteins are judged to be products of holB.     

The isolation of nonsense mutations in cell division cycle genes of the yeast Saccharomyces cerevisiae

Summary Nonsense mutations have been isolated in cell division cycle genes in a strain of Saccharomyces cerevisiae that carries a temperature-sensitive amber suppressor. These mutants may be valuable in identifying the products of genes involved in the cycle and in determining the pattern of their synthesis during the cell cycle.     

Plasmodium gallinaceum: induction of male gametocyte exflagellation by phosphodiesterase inhibitors.

The phosphodiesterase inhibitors, Squibb 20009, caffeine, and 8-bromo-cyclic adenosine monophosphate (8-bromo-cAMP) are capable of stimulating gametogenesis, thus implicating cyclic nucleotides in the initiation of this process. Squibb 20009 and 8-bromo-cAMP stimulated gametogenesis at pH 8.0 but not at pH 7.4 whereas caffeine stimulated gametogenesis at pH 8.0 and 7.4.     

Immunospecific labeling of mouse lymphocytes in the scanning electron microscope

Bone marrow-derived (B) and thymus-derived (T) Balb/c mouse lymphocytes were identified in the scanning electron microscope (SEM) by the immunospecific attachment of one of several kinds of large-molecular-weight markers distinguishable in SEM. These markers (tobacco mosaic virus, keyhole limpet hemocyanin, bushy stunt virus, and bacteriophage T4) could be modified with hapten groups and linked with anti-hapten antibody, in an indirect (sandwich) scheme, to hapten-modified anti-cell-surface antibody bound to the cell surface. Hapten-modified antibodies to B cell antigens (goat anti-mouse-immunoglobulin) or to T cell antigens (rabbit anti-mouse brain) were employed to identify these two lymphoid cell types in unfractionated spleen, mesenteric lymph node, bone marrow, and thymus cell populations. The topography of B cells was always indistinguishable from that of T cells. No surface features were found to be unique to either cell type. In suspension, the majority of B and T cells had one or no microvilli regardless of the tissue source of the labeled cells. Cells in suspension that had microvilli (usually 10% of the total cell population) were always unlabeled. However, after cell contact with a glass surface, approximately half of both the B and T cell populations had a villous topography.     

Iron Metabolism in the Anaemia of Chronic Renal Failure. Effects of Dialysis and of Pareuteral Iron

Serial studies of iron transport in patients on maintenance dialysis showed normal or raised values in almost all subjects and a transient increase soon after the start of dialysis in three. These patients, who were seldom or never transfused, had low serum iron levels and normal iron-binding capacity with low saturation. Iron transport was substantially increased by parenteral iron-dextran treatment. Tracer studies showed good iron utilization, with transport to the marrow rather than to the liver. In these circumstances iron therapy is safe and beneficial, and a useful rise in red cell mass was shown to result from it. The packed cell volume was found to be a valid index of red cell mass in these patients. Red cell loss in the dialysers was insufficient to account for the observed reduction in red cell survival.     

Insulin Infusion Test of Gastric Acid Secretion

In view of the disadvantages of the standard insulin test for completeness of vagotomy a continuous insulin infusion test has been developed. Twenty-six tests were carried out on 12 healthy male volunteers. A dose of 0·04 unit of soluble insulin/kg/hr was found to produce the highest acid secretion with the least severity of symptoms of hypoglycaemia. The pattern of response was a plateau of acid secretion and of hypoglycaemia, and repeated studies in six subjects showed that the results were reproducible. Evaluation of this test after vagotomy and comparison with the standard insulin test are now required.