Photolysis and ozonolysis of (iso) desmosine-containing crosslinked peptides from porcine aorta elastin

This report describes the use of photolysis and ozonolysis as a means of achieving complete cleavage of the pyridinium ring of (iso)desmosine in crosslinked elastin peptides. Although photolysis leads to the opening of the ring with concomitant formation of lysine, the peptide chains remain attached. Subsequent ozonolysis is able to completely achieve the cleavage of the rest of the ring skeleton, thus leading to the separation of the peptide chains. Formation of new amino acids, i.e. α-aminoadipic and glutamic acids, is emphasized. Localization of these amino acids within the released peptides should be of help in structural investigations on the crosslinking zones involving either isodesmosine or desmosine. However, other amino acids such as tyrosine and phenylalanine are sensitive to this procedure and side reactions occur which are responsible for peptide bond cleavage with the formation of breakdown products.     

The diagnosis of cutaneous T-cell lymphoma by morphometric evaluation of the cellular infiltrate, using semithin sections

In order to improve the cytological criteria for the diagnosis of cutaneous T-cell lymphomas (CTCL), a number of morphometric assessments in semithin sections have been performed on the dermal infiltrates of twenty-one cases of overt CTCL (group I) and twenty-two cases of well-defined benign dermatoses (group II). In each biopsy, an average of 250 cells were measured for perimeter (P), surface area (S), 'nuclear shape index' (NSI), mean surface and mean NSI. We also determined the percentage of typical 'highly cerebriform lymphocytes' (HCL). Cells of group I patients were found to have mean S and mean NSI that differed significantly from those of group II. HCL were found to have a mean NSI value of less than 0.40. The diagnostic value of these measurements was confirmed in the group I patients. Nineteen of them had a mean NSI value of less than 0.61, together with a mean S greater than 14 sq. micron. None of the twenty-two patients of group II had such values. The discriminating power of these criteria was then tested retrospectively on another group of initially controversial patients who presented with suspected CTCL (group III patients). Nine have since evolved into overt CTCL (group III M) while the other ten have remained benign (group III B). All group III B patients and five patients of group III M were correctly assigned using the above morphometric criteria. This method could improve the diagnosis of the early stage of cutaneous T-cell lymphoma.     

COMPARISON OF SEVEN STAINING METHODS FOR SENILE PLAQUES AND NEUROFIBRILLARY TANGLES IN A PROSPECTIVE SERIES OF 15 ELDERLY PATIENTS

Samples of brain from 15 prospectively tested women over 75 years of age, living in the same institution and with a Blessed test score between 0 and 28 were studied to evaluate seven different staining techniques for counting senile plaques and neurofibrillary tangles. The methods included Bielschowsky (modified by Yamamoto & Hirano, 1986), Cross, Gallyas, Naoumenko-Feigin, silver methenamine, Bodian coupled with luxol fast blue, and thioflavine S; these techniques were performed on contiguous slides of the first temporal gyrus (Brodmann's area 22). The cost, difficulty and variability of the methods were evaluated. Modified Bielschowsky method revealed both amyloid and neurites. Cross, Bodian and Gallyas stained neurites preferentially and were more sensitive for neurofibrillary tangles than for senile plaques. Silver methenamine revealed amyloid in much the same way as thioflavine S. The highest count of senile plaques and neurofibrillary tangles was obtained with the modified Bielschowsky method. Best correlations between density of senile plaques and Blessed test score were obtained with modified Bielschowsky impregnation, silver methenamine, and Bodian and those for neurofibrillary tangles, with modified Bielschowsky, Naoumenko-Feigin, and Gallyas methods. Naoumenko-Feigin impregnation, even if fitted to the linear model, revealed very few changes (four times less than modified Bielschowsky) and appeared to be insensitive. All the techniques except Naoumenko-Feigin, were equally able to distinguish two groups of cases, i.e. those affected by Alzheimer's disease and those not affected. A multiple regression analysis indicated that the statistical relationship between the density of changes, evaluated after the modified Bielschowsky method, and the Blessed test score could not be improved by the additional use of other staining techniques. These data have direct implications for the evaluation of diagnostic criteria in Alzheimer's dementia. In this study, modified Bielschowsky impregnation was found to give the most complete picture of the lesions and, as such, could be considered a reference method. This technique is, however, expensive and difficult to perform. It stains a large number of normal structures and the recognition of the lesions is more subjective than with other selective stains. It is therefore difficult to recommend this technique for routine use. Other techniques alone, or in combination, can be recommended but the diagnostic criteria should be adapted for each of them.