Comparison of the pathology of cerebral white matter with post-mortem magnetic resonance imaging (MRI) in the elderly brain.

White matter lesions (WML) on magnetic resonance imaging (MRI) brain scans are associated with ageing. They are unrelated to specific disorders, and their impact on cognitive and other brain functions is poorly characterized. Pathological studies often omit systematic survey of WML because of the need to study multiple full coronal tissue blocks, and uncertainty over the significance of lesions identified in periventricular and deep subcortical regions. Post-mortem MRI provides a means of mapping WML but the sensitivity and specificity of the method are unresolved. In this study post-mortem MRI of WML in fixed brain slices was compared with pathology in 33 brains donated to the Medical Research Council Cognitive Function and Ageing Study (MRC CFAS). This study shows that MRI detection of WML was less sensitive than pathology: periventricaular lesions (PVL) sensitivity = 95% (87-99%), specificity = 71% (44-90%); deep subcortical lesions (DSCL) sensitivity = 86% (79-93%), specificity = 80% (72-88%). False negative MRI was associated with milder pathology, but lesions detected by myelin attenuation alone showed both microglial and endothelial activation. Therefore post-mortem MRI of formalin-fixed brain slices is a reliable method to obtain systematic data on the severity and distribution of cerebral white matter disease, and appears to detect those WML most likely to have clinical impact.

Vasopressin stimulation of cell proliferation in the rat pituitary gland in vitro.

Proliferative activity was measured in rat anterior pituitary cells in short-term culture by calculating the labelling index (LI), based on the immunohistochemical detection of cells incorporating the thymidine analogue bromodeoxyuridine. Basal LI was reproducible in the test system. Arginine vasopressin (AVP) induced a dose-related increase in LI up to 20 ng/ml. Corticotrophin-releasing factor-41 (CRF-41) had no effect at doses up to 20 ng/ml. However, in the presence of 10 ng CRF-41/ml, AVP induced a greater increase in LI at lower doses than did AVP alone. Fibroblast growth factor also induced a significant increase in LI. In the system used, epidermal growth factor and insulin had no effect on proliferation.

Nucleolar organiser regions in colonic dysplasia. A preliminary study.

As a preliminary investigation in the evaluation of the argyrophilic nucleolar organiser region (AgNOR) technique in colonic dysplasia, quantitation of AgNORs was carried out in biopsies of normal rectal mucosa and tubulovillous adenomas. The AgNOR counts in the lower third of the normal crypts were approximately twice those in the surface mucosa but there was no significant difference between counts in normal crypt bases and adenomas. It is concluded that the AgNOR technique is unlikely to be of value in the assessment of colonic dysplasia.

Association between CAM 5.2 and anti-CD1a reactivity in lymph nodes and gastrointestinal tract epithelium.

Immunocytochemical studies, using the antibodies CAM 5.2 and NA1/34 (CD1a), were performed on normal lymphoid tissue and malignant lymphomas. A population of dendritic cells in the paracortex of lymph nodes and in T cell lymphomas reacted with both antibodies. Colocalisation with antibodies was also found in gastrointestinal epithelium. Immune blotting shows that the likely basis of this reactivity is a 12 kilodalton peptide which is recognised by both antibodies. This is almost certainly the beta t peptide which has been described as the light chain of CD1a.

Nucleolar organiser regions in pituitary adenomas.

Nucleolar organiser regions have been identified by a silver-staining technique (AgNORs) and quantified in paraffin sections of normal foetal and adult pituitary gland and in a series of 35 pituitary adenomas, which included all the main types. In the adult pituitary there were 1.45 +/- 0.07 (mean +/- SEM) AgNORs per cell and in the foetal gland 2.94 +/- 0.37. The overall values for the adenomas were 1.98 +/- 0.08. Macroadenomas had significantly higher numbers (2.18 +/- 0.09) than microadenomas (1.69 +/- 0.11). Of the hormonally active tumours, corticotroph adenomas had the highest value (2.18 +/- 0.15), although four out of six were microadenomas.

Combined immunocytochemistry and nucleolar organizer region staining: some technical aspects.

We have examined the feasibility of combining immunocytochemistry with argyrophilic staining of nucleolar organizer regions (AgNORs) on a single preparation. The combined technique gave positive results on fixed tissues, with immunoalkaline phosphatase methods providing better contrast. On frozen sections, there were problems with adhesion and with immunostaining. Delayed fixation did not affect AgNOR staining, suggesting that the technique may be applied to autopsy tissue. Trypsinisation of sections did not alter the count of silver stained granules.