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B D Beck

Publications and source records attributed to B D Beck.

44 records · Page 3Linked to original sources
PubMed1981

The pulmonary toxicity of an ash sample from the MT. St. Helens Volcano.

Volcanic ash was collected from the Moses Lake region of Washington State after the 18 May 1980 eruption of Mt. St. Helens. The ash was tested in a short-term bioassay system using hamsters exposed by intratracheal instillation. One day after exposure the lungs were lavaged and the fluid collected was characterized using several parameters that represent different manifestations of lung injury: (a) in situ phagocytic ability of pulmonary macrophages; (b) the inflammatory response, as shown by polymorphonuclear neutrophil numbers and albumin levels in lung lavage fluid; and (c) release of cytoplasmic and lysosomal enzymes into the cell-free supernatant of lung-lavage fluid. The response to volcanic ash was elevated compared to controls, but was similar to the response to Al2O3, a dust considered to be relatively inert. In contrast, the response to alpha-quartz, a highly toxic fibrogenic dust, was significantly greater than the response to either volcanic ash or Al2O3 for most parameters measured.

Air Pollutants↗
PubMed1979

Polymerization of the bacterial elongation factor for protein synthesis, EF-Tu.

The bacterial elongation factor for protein synthesis, EF-Tu, polymerizes into fibrils at pH 6.0. These fibrils are 0.7 microM in diameter, at least 200 microns in length, and are positively birefringent. Electron microscopic observations of negatively stained images demonstrates that the EF-Tu fibrils consist of bundles of individual filaments, approximately 5nm in diameter, aligned parallel to the long axis of the fibril. Polymerized EF-Tu exchanges nucleotide rapidly and interacts with the other elongation factor, EF-Ts. The antibiotic kirromycin induces the polymerization of EF-Tu into fibrils and even larger structures under nonpolymerizing conditions.

Guanosine Diphosphate↗
PubMed1978

Novel properties of bacterial elongation factor Tu.

We have characterized novel properties of the bacterial protein synthesis elongation factor Tu which indicate that it may function as a structural protein. Under appropriate conditions, elongation factor Tu polymerizes to form filaments and, more often, bundles of filaments. It is also the predominant component of a complex of proteins from Escherichia coli that undergoes reversible polymerization in the presence of KCl and MgCl2. In addition, purified elongation factor Tu binds tightly to DNase I in the presence of 10 mM MgCl2. In crude extracts the factor shows no binding in the presence or absence of MgCl2. These properties suggest that elongation factor Tu may have certain actin-like properties and that it has cellular functions other than its role in protein synthesis.

Bacterial Proteins↗
PubMed1977

Basis for the observed fluctuation of carboxypeptidase II activity during the cell cycle in BUG 6, a temperature-sensitive division mutant of Escherichia coli.

Diaminopimelyl-d-alanyl carboxypeptidase (carboxypeptidase II) is most active at the time of division, whether measured in toluene-treated cells of Escherichia coli K-12 strain D11-1, fractionated by size, or in toluene-treated cells of the temperature-sensitive division mutant, BUG 6 (B. D. Beck and J. T. Park, 1976). The present investigation has now shown that, under conditions that permit division, the increased carboxypeptidase II activity in toluenetreated cells of BUG 6 is probably not due to protein synthesis. Although dividing cells are more permeable than nondividing cells, permeability differences are not sufficient to account for the changes in carboxypeptidase II activity. Thus, in the toluene-treated nondividing cells, carboxypeptidase II is present, but its activity is masked, which suggests the presence of an inhibitor. Another striking difference between nondividing and dividing cells is that carboxypeptidase II is much more readily released from dividing cells by both tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetic acid and toluene treatment. Carboxypeptidase II was partially purified and found to be an 86,000-molecular-weight protein consisting of two 43,000-molecular-weight polypeptides. Tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetic acid treatment of nondividing cells releases less than 10% of the carboxypeptidase II and other periplasmic proteins that are releasable from dividing cells.

Carboxypeptidases↗
PubMed1976

Activity of three murein hydrolases during the cell division cycle of Escherichia coli K-12 as measured in toluene-treated cells.

The specific activities of three murein hydrolases, carboxypeptidase I, carboxypeptidase II, and amidase were studied with respect to cell division in toluene-treated cells of Escherichia coli K-12. Carboxypeptidase I and amidase activities were constant throughout the division cycle in cells of D11/lac+pro+. Detectable carboxypeptidase II activity varied and was highest at the time of division by a factor of three. Carboxypeptidase II specific activity was also correlated with cell division in BUG 6, a temperature-sensitive mutant (J.N Reeve, D.J. Groves, and D.J. Clark, 1970). Fifteen minutes after shifting BUG 6 from 42 C (nondividing conditions) to 32 C (dividing conditions), there was a rapid resumption of cell division, accompanied by a 10-fold increase in the specific activity of carboxypeptidase II. These results demonstrate a correlation between detectable carboxypeptidase II activity and cell division as reflected by activity in toluene-treated cells. The subcellular location of carboxypeptidase II, a soluble enzyme was found to be periplasmic since it was released by tris(hydroxymethyl)-aminomethane-ethylenediaminetetraacetate treatment and osmotic shock, two methods known to release periplasmic enzymes.

Amidohydrolases↗
PubMedDate not supplied

Recent trends in childhood blood lead levels.

Blood lead levels in children in the United States have declined through 1994, the date of the most recent National Health and Nutrition Examination Survey. In this investigation, the authors analyzed whether blood lead levels have changed since 1994 and quantified the magnitude of any change. The authors evaluated blood lead levels from 12 longitudinal data sets from 11 states and 1 city. Geometric mean blood lead levels declined between 4%/year and 14%/year in 8 of the data sets. No differences in decline rates were observed between data sets from states that had universal screening as a goal or that included repeat measures for an individual child and those data sets that did not. The authors' best estimate for these populations was a decline rate of 4-7%/year, which was comparable to the decline rate prior to 1994.

Adolescent↗