Frequency and clinical significance of simultaneous association of lobular neoplasia and columnar cell alterations in breast tissue specimens.

Lobular neoplasia (LN) and columnar cell alterations (CCAs) may share similar genetic abnormalities, but there is no appreciable literature that addresses the simultaneous occurrence of these lesions in breast core biopsy (CNB) specimens or resection specimens. Three groups of breast tissue were examined: group 1, 68 CNB specimens targeted for "suspicious" microcalcifications (Breast Imaging Reporting and Data System [BI-RADS] 4) and diagnosed with LN; group 2, 2,516 CNB reports for a 1-year period; and group 3, 400 consecutive breast carcinoma resection specimens analyzed for LN and CCAs within the vicinity of carcinoma. In group 1, LN was associated with CCAs in 54% of cases (37/68). In group 2, LN was found in association with CCA in 1.3% of cases (32/2,516). In group 3, 13.0% of cases of CCAs (52/400) were associated with LN. Our study suggests the association of these two lesions in breast tissue is nonrandom and that they may have a common progenitor pathway of neoplastic development.

Laboratory evaluation of a protocol for personal sampling of airborne particles in welding and allied processes.

A new European/International Standard (ISOprEN 10882-1) on the sampling of airborne particulates generated during welding and allied processes has been proposed. The use of a number of samplers and sampling procedures is allowable within the defined protocol. The influence of these variables on welding fume exposures measured during welding and grinding of stainless and mild steel using the gas metal arc (GMA) and flux-cored arc (FCA) and GMA welding of aluminium has been examined. Results show that use of any of the samplers will not give significantly different measured exposures. The effect on exposure measurement of placing the samplers on either side of the head was variable; consequently, sampling position cannot be meaningfully defined. All samplers collected significant amounts of grinding dust. Therefore, gravimetric determination of welding fume exposure in atmospheres containing grinding dust will be inaccurate. The use of a new size selective sampler can, to some extent, be used to give a more accurate estimate of exposure. The reliability of fume analysis data of welding consumables has caused concern; and the reason for differences that existed between the material safety data sheet and the analysis of fume samples collected requires further investigation.

Differential silver-staining sodium dodecyl sulfate-polyacrylamide gel electrophoresis: a nonisotopic method for characterizing gel-separated histone-DNA complexes.

Some nonspecific, DNA-binding proteins, like the linker histones, precipitate DNA upon binding. This is a poorly understood process that limits analysis of such nucleoprotein complexes using standard gel electrophoresis. To circumvent this problem, low concentrations of glutaraldehyde were used to crosslink the linker histones to DNA; then the partially crosslinked complexes were solubilized in SDS2 and separated by SDS-PAGE. Differential detection was accomplished using two different silver staining protocols that preferentially stained either proteins or nucleic acids. A technique was developed which allows the relative proportion of linker histones and DNAs in each detected band to be determined, and is referred to as differential staining SDS-PAGE (DS-SDS-PAGE). DS-SDS-PAGE provides a novel, non-isotopic means for characterizing multiple nucleoprotein bands separated by polyacrylamide gel electrophoresis. In applying this method to a model linker histone-DNA study, we were able to detect both protein-DNA and protein-protein contacts that are important in linker histone assembly onto DNA.

Self-association of linker histone H5 and of its globular domain: evidence for specific self-contacts.

The ability of avian-specific linker histone H5, and the globular domains of H5 (GH5) and H1(0) (GH1(0), to self-associate either free in solution or when bound to DNA was investigated. All three proteins underwent a salt-dependent increase in turbidity that may be indicative of nonspecific interactions. Dithiobis(succinimidyl propionate) cross-linking was used to measure specific contacts for both H5 and GH5 free in solution and bound to DNA. H5 and GH5 each became cross-linked in solution, with GH5 displaying divalent polymerization interactions, which suggests that two specific surfaces were involved in the assembly process. For GH5-DNA complexes, cross-linking appeared to be largely the consequence of aggregation, but under low concentrations of DSP, cross-linking GH5 was observed to assemble preferentially onto DNA before oligomerizing to form massive aggregates. Both linear and supercoiled DNA facilitated GH5 interactions compared to assembly in solution; differences in the distribution of cross-linked polymer sizes indicates that assembly is dependent on both the presence of DNA and the morphology of the DNA. Finally, on the basis of a technique referred to as quantitative proteolysis, GH5 assembly on DNA appears to involve specific protein-protein contacts involving the C terminus of one partner. Overall, the cumulative results reported here support the premise that linker histones assemble specifically both in solution and on DNA.

Double pylorus: a complication of chronic gastric ulcer?

A case of double pylorus with a chronic ulcer in one of the two channels is described. The patient, a middle-aged man with active rheumatoid arthritis, required partial gastrectomy to allow continued treatment of the arthritis with anti-inflammatory drugs. Detailed histological examination of the surgical specimen revealed features consistent with intramural penetration of an ulcer across the pyloric ring, resulting in a gastro-duodenal fistula. The findings provide further support for the hypothesis that the double pylorus is an acquired lesion, which occurs as an uncommon complication of chronic peptic ulcer.