Virtual microscopy for histology quality assurance of screen-detected polyps

AIM

Histology quality assurance is crucial for screening programmes and can be performed by circulating glass slides, which has certain intrinsic disadvantages. The present study aimed to assess the accuracy of virtual microscopy in terms of reliability and diagnostic reproducibility in colorectal cancer screening programmes.

METHODS

457 consecutive lesions detected in people undergoing colonoscopy were examined histologically in two pathology units, using both traditional optical microscopy and virtual microscopy (6-12 months later). Intra- and inter-observer agreement using the two approaches was determined using κ statistics.

RESULTS

Intra- and inter-observer agreements were substantially unmodified by the use of the virtual microscopy approach compared with traditional optical microscopy; moreover, for some histological features critical for patient management in colorectal cancer screening programmes (such as the presence of a villous component within the adenoma), virtual microscopy increased interobserver agreement (κ statistics 0.66 versus 0.52).

CONCLUSIONS

This study shows that virtual microscopy can be an effective tool for diagnostic quality assurance in colorectal cancer screening programmes, and its accuracy is equivalent to or higher than that of optical microscopy in the validation of histological criteria (eg, advanced adenoma) crucial for patient management in screening programmes.

Acute hyperparathyroidism: our experience with 36 cases

OBJECTIVES

Acute hypercalcemia is a serious condition and represents a physician-surgical emergency: the difficulty in setting a precise diagnosis is due to several possibilities that can cause the condition. It is our purpose to critically evaluate the most actual schemes of treatment and the conditions that could favour the appearance of a hypercalcemic acute crisis.

MATERIALS AND METHODS

A retrospective study was performed considering 1321 patients (638 primary HPT, 683 secondary or tertiary HPT) operated from 1975 to December 2002 for Primary, Secondary and Tertiary HPT.

RESULTS

It should be noticed that out of 638 cases of Primary HPT this syndrome was present in 35 patients (Ca higher than 15 mg/dl): if you compare these cases with the hyperparathyroid population with calcium less than 15 mg/dl it is possible to observe that a double adenoma or a carcinoma were more frequently found in acute HPT, as the cystic appearance of the lesion. The weight of the adenoma and the PTH assay are strictly correlated with the appearance of this syndrome. The mortality rate is also higher (2.8% to 0.1%) than in the hyperparathyroid patient who underwent parathyroidectomy without hypercalcemic crisis.

CONCLUSION

These characteristics suggest that an early operation is mandatory in the patients in whom such a possibility could be expected, before serious involvement of the cardiovascular, renal or neuromuscular system. We can point out the rarity of this syndrome in Secondary and Tertiary HPT: just one case in Secondary out of 683 patients operated on from 1975 until December 2002.

[Surgical treatment of secondary and tertiary hyperparathyroidism]

AIMS

To determine whether, in secondary and tertiary hyperparathyroidism (HPT), quick parathyroid hormone (PTH) assay can be used to prevent persistent or recurrent HPT. Another point was to determine, considering the PTH decrease, the cut-off point at which the operation could be considered well performed.

METHODS

A retrospective study was performed evaluating all cases operated on since 1975 until 2002, 679 patients, and particularly the analysis of two groups of patients that underwent surgical treatment for secondary and tertiary HPT in the period 1995-2002. In the first group, (January 1995-October 1999) 207 (167 HPT II and 40 HPT III) neck explorations were performed without the aid of quick PTH assay; in the second group (November 1999-December 2002), 192 (153 HPT II and 39 HPT III) patients were operated on with blood samples for quick PTH.

RESULTS

In the first group the percentage of success for secondary HPT was 93.8 versus 96.2 of the second group and 91.7 versus 94.2 for tertiary HPT. In reoperations the percentage of success was 72.7 in the first group and 87.5 in the second one.

CONCLUSIONS

There are no substantial differences in persistences or recurrences between subtotal or total parathyroidectomy (PTx) with autotransplantation (AT). The choice of the gland to be left in the neck or transplanted in the forearm and the modalities of doing so are very important, considering the macroscopical and histological aspects. Intraoperative PTH monitoring is a useful aid during the first cervical exploration for secondary and tertiary HPT to prevent the development of persistent or recurrent HPT. The cut-off point for secondary HPT is 70% (in difficult cases with more than 2 assays, 75%) and for tertiary HPT 50% and 70% respectively.

Metabolic stress opens K+ channels in hepatoma cells through a Ca2+- and protein kinase calpha-dependent mechanism

These studies of a model liver cell line evaluate the mechanisms responsible for regulated release of K+ ions during metabolic stress. Metabolic inhibition of HTC hepatoma cells by exposure to 2, 4-dinitrophenol (50 microM) and 2-deoxy-D-glucose (10 mM) stimulated outward currents carried by K+ of 974 +/- 75 pA at 0 mV (n = 20, p < 0.001). Currents were inhibited by chelation of intracellular Ca2+ or exposure to apamin (50 nM), an inhibitor of SKCa channels. In cell-attached recordings from intact cells, removal of metabolic substrates (25/28 cells) or exposure to metabolic inhibitors (32/40 cells) opened K+-selective channels with a conductance of 6.5 +/- 0. 2 pS. Channels had an open probability of 0.31 +/- 0.08 and opened in bursts averaging 3.55 +/- 0.27 ms in duration (n = 6). Metabolic stress was associated with rapid translocation of the alpha isoform of protein kinase C (PKCalpha) from cytosol to membrane; and down-regulation of PKCalpha by phorbol esters or exposure to the PKC inhibitor chelerythrine (10 microM) each inhibited currents. Moreover, intracellular perfusion with purified PKCalpha activated currents in a Ca2+- and concentration-dependent manner. These findings indicate that metabolic stress leads to opening of apamin-sensitive SKCa channels in hepatoma cells through a Ca2+- and PKC-dependent mechanism and suggest that PKCalpha may be selectively involved in the response. This mechanism functionally couples the metabolic state of cells to membrane K+ permeability and represents a potential target for modification of liver injury associated with ischemia and preservation.

Bombesin binding and biological effects on pancreatic acinar AR42J cells

The effects of bombesin on amylase release and the receptor binding of 125I-[Tyr4]bombesin in the rat pancreatic acinar carcinoma cell line AR42J were examined. Bombesin-like peptides stimulated amylase release from AR42J cells in a dose-dependent manner; a maximal 2-fold stimulation occurred at a bombesin concentration of 300 pM. Binding of 125I-[Tyr4]-bombesin to AR42J cells was specific, saturable and temperature dependent. The relative potencies with which various structurally related peptides stimulated amylase release correlated well with their relative abilities to compete for the bombesin receptor.