Dementia with Lewy bodies.

Dementia with Lewy bodies (DLB) is the recommended term for a common cause of dementia characterized by the histological presence of distinctive inclusions within neurons, Lewy bodies (McKeith et al, 1996). Following increasing pathological recognition, core clinical diagnostic features have been identified to allow diagnosis in life. Insights into the biology of this type of neurodegeneration suggest that the regional patterns of involvement might allow therapeutic intervention. Although Lewy bodies had long been recognized in the substantia nigra and other subcortical nuclei in patients with Parkinson's disease (PD), it was only in the 1970s that a significant number of reports began to be published from Japan describing patients with dementia and parkinsonism associated with the presence of Lewy bodies in cortical neurons (reviewed by Kosaka, 1990). Since these reports, different workers have used a variety of terms to describe this disease process, including diffuse Lewy body disease (Yoshimura, 1983), Lewy body dementia (Gibb et al, 1987), senile dementia of Lewy body type (Perry et al, 1990a) and the Lewy body variant of Alzheimer's disease (Hansen et al, 1990).

Laser Doppler perfusion imaging of skin blood flow using red and near-infrared sources.

At present, scanning laser Doppler imaging uses a 633-nm helium-neon laser (RED) as the only light source, but this restricts its ability to measure blood flow (i) at darkly pigmented skin and (ii) from deeper or subdermal structures. Because near-infrared (NIR) light is known to penetrate deeper into tissue and to be less absorbed than RED, two imagers were adapted to include a NIR laser diode source (one of 830 nm for UK studies; one of 780 nm for leprosy field trials) in parallel with the existing RED source. In human hands representing a range of skin pigmentations, RED scans were unobtainable at the darkest areas of skin, but intact NIR scans could be collected in all cases. In experiments at the rat knee and the dorsal human hand, NIR and RED values were similar on normal skin. Over underlying vessels, however, NIR values greatly exceeded RED values, an effect abolished by occlusion. Similarly, in patients with leprosy and in healthy controls in Spain, fingerpulp NIR values exceeded RED values to the greatest degree when thermoregulatory flow was highest, i.e., when the deeper-lying arteriovenous anastomoses were open. Over areas of experimental inflammation, NIR gave higher values and also exhibited a greater degree of spatial heterogeneity than RED. We conclude that some current limitations of laser Doppler imaging technology can be overcome by the use of NIR laser diode sources.

Diversity in migration of CD4 and CD8 lymphocytes in different microanatomical compartments of the skin in the tuberculin reaction in man.

The lymphocytes in the perivascular foci of tuberculin skin tests have a similar CD4:CD8 ratio to those in the peripheral blood, suggesting that these subsets do not show bias in their initial emigration. By contrast, the diffusely infiltrating lymphocytes show a relative preponderance of CD4 cells which is progressively greater in successive 250 micron layers into the dermis. A generally similar pattern is seen in healthy controls and in patients with untreated pulmonary tuberculosis, treated leprosy, haemophilia A and chronic obstructive lung disease (COLD) patients treated with prednisolone, but the gradient of increasing CD4:CD8 ratio with depth into the dermis is significantly less steep in patients with tuberculosis, haemophilia and prednisolone-treated COLD than in the healthy controls. Selective migration results in a relative preponderance of CD4 cells in the diffuse infiltrate and it is suggested that this is a mechanism likely to potentiate defensive reaction to Mycobacterium tuberculosis: any deficiency in selective migration may make immunological defences less effective and so contribute to the chronicity of the lesions of tuberculosis.