Enterprise Implementation of Digital Pathology: Feasibility, Challenges, and Opportunities

Digital pathology is becoming technically possible to implement for routine pathology work. At our institution, we have been using digital pathology for second opinion intraoperative consultations for over 10 years. Herein, we describe our experience in converting to a digital pathology platform for primary pathology diagnosis. We implemented an incremental rollout for digital pathology on subspecialty benches, beginning with cases that contained small amounts of tissue (biopsy specimens). We successfully scanned over 40,000 slides through our digital pathology system. Several lessons (both challenges and opportunities) were learned through this implementation. A successful conversion to digital pathology requires pre-imaging adjustments, integrated software and post-imaging evaluations.

Mutant allele-specific imbalance modulates prognostic impact of KRAS mutations in colorectal adenocarcinoma and is associated with worse overall survival

The prognostic impact of distinct KRAS mutations in colorectal carcinomas is not fully characterized. We hypothesized that the prognostic impact of KRAS mutations is modulated by KRAS mutant allele-specific imbalance (MASI). KRAS MASI was assessed by sequencing electropherograms in KRAS-mutated colorectal carcinomas (N = 394, prospectively tested). The mechanism of KRAS MASI was studied by fluorescence in situ hybridization (FISH; N = 50). FISH showed that KRAS MASI developed by chromosome 12 hyperploidy (9/18, 50%) or KRAS amplification (1/18, 5.5%). KRAS MASI was more common in tumors with KRAS codon 13 than with codon 12 mutations [24/81, 30% vs. 54/313, 17%; odds ratio (OR), 2.0, 95% confidence interval (CI), 1.2-3.5; p = 0.01]. KRAS MASI was correlated with overall survival (N = 358, median follow-up = 21 months). In a multivariate analysis, KRAS codon 13 MASI was an independent adverse prognostic factor (compared to codon 13 mutants without MASI combined with all codon 12 mutants; adjusted hazard ratio, 2.2, 95% CI: 1.2-3.9; p = 0.01). KRAS MASI arises through chromosome 12 hyperploidy or KRAS amplification and, when affects KRAS codon 13, is associated with worse overall survival.

cDNA cloning and efficient mitochondrial import of pre-mtHSP70 from rat liver

Members of the 70-kD heat shock protein family have been found in all free-living organisms investigated and in major compartments of eukaryotic cells where they are essential to a wide range of functions, including protein folding and targeting. We have isolated a mitochondrial homolog (mtHSP70) from rat liver using ATP agarose affinity chromatography. Its identity was confirmed on the basis of immunological analysis and Ca(2+)-dependent autophosphorylation. Using protein sequence obtained from the amino termius and nine endo Lys-C peptide fragments, we have employed oligonucleotides to isolate a full-length cDNA clone. The open reading frame encodes a protein of 679 amino acids and calculated M(r) 73,913 daltons. The sequence has a high degree of identity with other members of the HSP70 family, including Escherichia coli DnaK (51%), Saccharomyces cerevisiae SSC1p (65%), the constitutive cytosolic HSP70 from rat, HSC70 (46%), and the rat endoplasmic reticulum isoform, BiP, (49%). The cDNA encodes a precursor protein with a 46-amino-acid signal peptide that is absent from the protein isolated from rat liver. The protein also shows a high degree of identity (98%) with a protein isolated from mouse and human tissues (PBP74, Domanico et al., 1993; mortalin, Wadhwa et al., 1993a; CSA, Michikawa et al., 1993a); however, the intracellular localization of these proteins is uncertain. We show that the precursor of mtHSP70 is efficiently imported into isolated mitochondria from rat liver and processed from 74 kD to the mature 69-kD protein.

Generation of a stable folding intermediate which can be rescued by the chaperonins GroEL and GroES

Pig heart mitochondrial malate dehydrogenase was chemically denatured in guanidine HCl. Upon 50-fold dilution of the denaturant spontaneous refolding could be observed in the temperature range 12-32 degrees C. At 36 degrees C spontaneous refolding was not observed but a stable folding intermediate that is fairly resistant to aggregation was formed. This intermediate is readily refolded by the chaperonins GroEL and GroES and may prove useful in future attempts to describe several aspects of chaperonin action at physiological temperatures.

The complete primary structure of rat chaperonin 10 reveals a putative beta alpha beta nucleotide-binding domain with homology to p21ras

The first complete amino-acid sequence of a mitochondrial chaperonin 10 is reported. The amino-terminal alanine residue is acetylated, a modification that may be required for the interaction with heptameric chaperonin 60. Part of the sequence constitutes a potential dinucleotide binding motif and is identical with 7 out of 10 residues in the GTP-binding site of p21ras. This similarity may be the structural basis for the recently discovered complex between p21ras and chaperonin 60 in intact cells (Ikawa, S. and Weinberg, R.A. (1992) Proc. Natl. Acad. Sci. USA 89, 2012-2016).

Substoichiometric amounts of the molecular chaperones GroEL and GroES prevent thermal denaturation and aggregation of mammalian mitochondrial malate dehydrogenase in vitro

The molecular chaperones GroEL and GroES were produced at very high levels in Escherichia coli, purified, and shown to protect pig mitochondrial malate dehydrogenase (MDH) against thermal inactivation in vitro. The apparent rate of MDH inactivation at 37 degrees C was reduced by a factor of at least 5 in a process which required only GroEL, GroES, and ATP. GroEL alone did not protect MDH against thermal inactivation but kept the denatured protein soluble and thereby prevented its aggregation. Reactivation of this soluble and inactive form of MDH could be achieved by addition of GroES even after 120 days of storage at -20 degrees C. Protection could be extended for more than 24 hr at 37 degrees C and was observed at molar ratios of chaperones to MDH as low as 1:4, suggesting that GroEL and GroES perform multiple turnovers in the absence of auxiliary chaperones. The availability of these chaperones in large quantities combined with the apparent promiscuity of GroEL binding shows great potential for stabilization of many proteins for which thermostable variants are not available. We speculate that GroEL and GroES perform similar protective roles in vivo and thereby increase the half-life of proteins which otherwise might aggregate under physiological conditions.

Heat shock proteins of barley mitochondria and chloroplasts. Identification of organellar hsp 10 and 12: putative chaperonin 10 homologues

Tissue slices from barley seedlings were subjected to heat shock and metabolically labelled with [35S]methionine and [35S]cysteine. Mitochondria and chloroplasts were isolated and shown to contain two novel heat shock proteins of 10 and 12 kDa, respectively. The possibility that these proteins, like a mitochondrial 10 kDa stress protein recently isolated from rat hepatoma cells [(1992) Proc. Natl. Acad. Sci. 89, in press] represent eukaryotic chaperonin 10 homologues is discussed.

Identification of a mammalian 10-kDa heat shock protein, a mitochondrial chaperonin 10 homologue essential for assisted folding of trimeric ornithine transcarbamoylase in vitro

We have identified a 10-kDa stress-inducible mitochondrial protein. The protein is synthesized at elevated rates in cultured rat hepatoma cells challenged with heat shock or amino acid analogues and, therefore, designated heat shock protein 10 (Hsp10). Hsp10 was purified to homogeneity from rat liver and found to exhibit a native molecular mass of 65 kDa, as opposed to a monomeric molecular mass of 10,813.4 +/- 0.41 Da. The amino acid sequence of rat Hsp10 disclosed extensive sequence similarity with bacterial chaperonin (Cpn) 10. Rat Hsp10 and Escherichia coli Cpn60 were used to reconstitute functional trimeric rat ornithine transcarbamoylase from a chemically denatured state with high efficiency. This process depended completely upon rat Hsp10 and was abolished in the presence of a nonhydrolyzable ATP analogue. We conclude that Hsp10 is a eukaryotic Cpn10 homologue and, therefore, together with Cpn60 essential for mitochondrial protein biogenesis. The Cpn-mediated protein-folding apparatus, thus, exhibits a high degree of conservation between prokaryotes and mitochondria of higher eukaryotes.

Evaluation of the biocompatibility of a Ni-Cr-Mo dental alloy with human gingival explant culture in vitro: morphological study, immunodetection of fibronectin, and collagen production

This study was undertaken to evaluate the biocompatibility of a Ni-Cr-Mo dental casting alloy by an in vitro explant culture method. Through ultrastructural features, the immunolabelling of fibronectin, and the immunodetection of type I and III collagen production, we investigated the behaviour of gingival cells (both fibroblasts and epithelial cells) in contact with the alloy in comparison with control cultures. Our results indicate that cultured gingival cells present a well preserved ultrastructure and synthesized fibronectin (the main glycoprotein involved in adhesion to substrates). The alteration of collagen production concerned only type III collagen which decreased significantly in the cultures on the dental alloy.