Thin, stubby or mushroom: spine pathology in Alzheimer's disease

Since their first description by Ramon y Cajal at the end of the 19th century, dendritic spines have been proposed as important sites of neuronal contacts and it has been suggested that changes in the activity of neurons directly affect spine morphology. In fact, since then it has been shown that about 90% of excitatory synapses end on spines. Recent data indicate that spines are highly dynamic structures and that spine shape correlates with the strength of synaptic transmission. Furthermore, several mental disorders including Alzheimer's disease (AD) are associated with spine pathology suggesting that spine alterations play a central role in mental deficits. The aim of this review is to provide an overview about the current knowledge on spine morphology and function as well as about different experimental models to analyze spine changes and dynamics. The second part concentrates on disease-relevant factors that are associated with AD and which lead to spine alterations. In particular, data that provide evidence that Abeta oligomers or fibrillar Abeta deposits influence spine morphology and function will be presented and the contribution of tau pathology will be discussed. The review ends with the discussion of potential mechanisms how disease-relevant factors influence dendritic spines and whether and how spine changes could be therapeutically suppressed or reversed.

Telomerase expression of malignant epithelial cells correlates with Dukes' stage in colorectal cancer

BACKGROUND

The ribonucleoprotein telomerase has been proposed as a potential prognostic marker for malignancy. Whether telomerase activity of clinical specimens correlates with other clinico-pathological variables, however, remains controversial. This is at least in part due to the varying contribution that nonmalignant cells will make to the net activity when extracts are assayed for telomerase activity. We therefore designed experiments to assay telomerase activity of isolated malignant cells of primary colorectal cancers.

METHODS

Thirty colorectal cancer and 20 corresponding specimen taken from macroscopically normal regions of the colon were mechanically disaggregated and digested with collagenase, DNase and hyaluronidase. The epithelial cell population was separated using Ber-EP4 pan-epithelial antibody and Magnetic Activated Cell Sorting technique. Haematoxylin and eosin staining was used to assess the proportion of recovered epithelial cells which were malignant. Telomerase activity was assayed by the Telomeric Repeat Amplification Protocol, which was quantified by PhosphorImager with Image Quant software.

RESULTS

Epithelial cells of three of 20 normal mucosa specimens were telomerase positive with weak activity (mean 3.7 TPGs, Total Product Generated, range 1.4-5.1TPGs). In the cancer group the vast majority (>95%) of the epithelial cells recovered were malignant by cytological criteria. Epithelial cells were telomerase positive in all the cancers, with a wide range of telomerase activity values (mean 22.7 TPGs, range 0.19-308 TPGs). Telomerase activity correlated with Dukes' stage (r = 0.52, P=0.004, Spearman's rank).

CONCLUSIONS

Pathological stage correlates with telomerase activity of the malignant cell population of the primary tumour in colorectal cancer. This suggests that telomerase activity increases during the progression of a cancer and may have implications for the design of anticancer (antitelomerase) agents.

The secret (GTN) of successful ERCP cannulation: a prospective randomised controlled study

BACKGROUND

A key step for success at endoscopic retrograde cholangio-pancreatography (ERCP) is cannulation of the sphincter of Oddi. This prospective randomised controlled study was conducted to assess the effect of glyceryl trinitrate (GTN) on ease of cannulation.

METHOD

Two hundred and fifty four patients undergoing ERCP were randomised into two groups, 126 controls and 128 pre-treated with GTN.

RESULT

There were 29 cannulation failures in the whole group (overall failure rate of 11.4%). Failure was significantly less common in the GTN group, 7.03% (9/128) as compared with 15.8% (20/126) in the control group (p=0.0002). Deep cannulation was desired but not achieved in 45/200 patients (22.5%) Of these, 18.4% (19/103) were in the GTN group versus 26.8% (26/97) in the control group. This pattern of difference applied to both trained and trainee endoscopists. No significant side effects of GTN were noticed.

CONCLUSION

GTN appears to be safe and effective in improving ERCP success rate. We recommend its routine use.

A lethal ectopic denture: an unusual case of sigmoid perforation due to unnoticed swallowed dental plate

We describe a case of generalised peritonitis due to sigmoid perforation caused by an unnoticed swallowed dental plate during sleep three months previously.