Cryo-Gel embedding compound for renal biopsy biobanking.

Optimal preservation and biobanking of renal tissue is vital for good diagnostics and subsequent research. Optimal cutting temperature (OCT) compound is a commonly used embedding medium for freezing tissue samples. However, due to interfering polymers in OCT, analysis as mass spectrometry (MS) is difficult. We investigated if the replacement of OCT with Cryo-Gel as embedding compound for renal biopsies would enable proteomics and not disturb other common techniques used in tissue diagnostics and research. For the present study, fresh renal samples were snap-frozen using Cryo-Gel, OCT and without embedding compound and evaluated using different techniques. In addition, tissue samples from normal spleen, skin, liver and colon were analyzed. Cryo-Gel embedded tissues showed good morphological preservation and no interference in immunohistochemical or immunofluorescent investigations. The quality of extracted RNA and DNA was good. The number of proteins identified using MS was similar between Cryo-Gel embedded samples, samples without embedding compound and OCT embedded samples. However, polymers in the OCT disturbed the signal in the MS, while this was not observed in the Cryo-Gel embedded samples. We conclude that embedding of renal biopsies in Cryo-Gel is an excellent and preferable alternative for OCT compound for both diagnostic and research purposes, especially in those cases where proteomic analysis might be necessary.

Value of α-methylacyl-CoA racemase immunochemistry for predicting neoplastic progression in Barrett's oesophagus.

AIM: To investigate the value of α-methylacyl-CoA racemase (AMACR) immunohistochemistry for predicting neoplastic progression in Barrett's oesophagus (BO). METHODS AND RESULTS: We conducted a case-control study within a prospective cohort of 720 BO patients. Patients who developed high-grade dysplasia or oesophageal adenocarcinoma were classified as cases, and patients without neoplastic progression as controls. AMACR expression was determined by immunohistochemistry in 12 127 biopsies from 635 patients, and was scored independently by two expert pathologists. Relative risks adjusted for age, gender, BO length and oesophagitis (RR(a)) were calculated in log-linear models. During a median follow-up of 6.6 years, 49 patients (8%) developed high-grade dysplasia or oesophageal adenocarcinoma. Although mild AMACR expression was associated with a trend towards an increased risk of neoplastic progression (RR(a) 1.6, 95% CI 0.9-3.1), the risk was especially elevated with strong AMACR expression (RR(a) 4.8, 95% CI 1.9-12.6). The positive predictive value of strong AMACR expression was slightly higher than that of low-grade dysplasia (22% versus 15%); the negative predictive value was slightly lower (91% versus 93%). CONCLUSIONS: Strong AMACR expression is associated with an increased risk of neoplastic progression in BO. However, AMACR expression appears to be a less powerful predictor for neoplastic progression than low-grade dysplasia.

Aberrant p53 protein expression is associated with an increased risk of neoplastic progression in patients with Barrett's oesophagus.

OBJECTIVE: The value of surveillance for patients with Barrett's oesophagus (BO) is under discussion given the overall low incidence of neoplastic progression and lack of discriminative tests for risk stratification. Histological diagnosis of low-grade dysplasia (LGD) is the only accepted predictor for progression to date, but has a low predictive value. The aim of this study was therefore to evaluate the value of p53 immunohistochemistry for predicting neoplastic progression in patients with BO. DESIGN: We conducted a case-control study within a prospective cohort of 720 patients with BO. Patients who developed high-grade dysplasia (HGD) or oesophageal adenocarcinoma (OAC) were classified as cases and patients without neoplastic progression were classified as controls. P53 protein expression was determined by immunohistochemistry in more than 12 000 biopsies from 635 patients and was scored independently by two expert pathologists who were blinded to long-term outcome. RESULTS: During follow-up, 49 (8%) patients developed HGD or OAC. P53 overexpression was associated with an increased risk of neoplastic progression in patients with BO after adjusting for age, gender, Barrett length and oesophagitis (adjusted relative risks (RR(a)) 5.6; 95% CI 3.1 to 10.3), but the risk was even higher with loss of p53 expression (RR(a) 14.0; 95% CI 5.3 to 37.2). The positive predictive value for neoplastic progression increased from 15% with histological diagnosis of LGD to 33% with LGD and concurrent aberrant p53 expression. CONCLUSIONS: Aberrant p53 protein expression is associated with an increased risk of neoplastic progression in patients with BO and appears to be a more powerful predictor of neoplastic progression than histological diagnosis of LGD.