Digital image analysis agrees with visual estimates of adult bone marrow trephine biopsy cellularity.

INTRODUCTION: Evaluation of cellularity is an essential component of bone marrow trephine biopsy examination. The standard practice is to report the results as visual estimates (VE). Digital image analysis (DIA) offers the promise of more objective measurements of cellularity. METHODS: Adult bone marrow trephine biopsy sections were assessed for cellularity by VE. Sections were scanned using an Aperio AT2 Scanscope and analyzed using a Cytonuclear (version 1.4) algorithm on halo software. Intraclass correlation (ICC) was used to assess relatedness between VE and DIA, and between MRI and DIA for a separate subset of patients. Trephine biopsy sections from a subset of patients with bone marrow biopsies uninvolved by malignancy were assessed for age-related changes. RESULTS: Interobserver VE agreement was good to excellent. The ICC value was 0.81 for VE and DIA, and 0.50 for MRI and DIA. Linearity studies showed no statistically significant trend for age-related changes in cellularity in our cohort (r = -.29, P = .06). CONCLUSIONS: Agreement was good between VE and DIA. It may be possible to use DIA or VE to measure cellularity in the appropriate clinical scenario. The limited sample size precludes similar determinations for MRI calculations. Further studies examining healthy donors are necessary before making definitive conclusions regarding age and cellularity.

Transcription of chromosomal rRNA genes by both RNA polymerase I and II in yeast uaf30 mutants lacking the 30 kDa subunit of transcription factor UAF.

UAF, a yeast RNA polymerase I transcription factor, contains Rrn5p, Rrn9p, Rrn10p, histones H3 and H4, and uncharacterized protein p30. Mutants defective in RRN5, RRN9 or RRN10 are unable to transcribe rDNA by polymerase I and grow extremely slowly, but give rise to variants able to grow by transcribing chromosomal rDNA by polymerase II. Thus, UAF functions as both an activator of polymerase I and a silencer of polymerase II for rDNA transcription. We have now identified the gene for subunit p30. This gene, UAF30, is not essential for growth, but its deletion decreases the cellular growth rate. Remarkably, the deletion mutants use both polymerase I and II for rDNA transcription, indicating that the silencer function of UAF is impaired, even though rDNA transcription by polymerase I is still occurring. A UAF complex isolated from the uaf30 deletion mutant was found to retain the in vitro polymerase I activator function to a large extent. Thus, Uaf30p plays only a minor role in its activator function. Possible reasons for slow growth caused by uaf30 mutations are discussed.