Current clinical laboratory practice: investigation of plasma lipids--which tests and when?

Clinical interest in the lipoproteins stems mainly from the association between serum cholesterol concentrations and coronary heart disease. Investigations of lipoproteins should be performed in patients with premature coronary heart disease, with a strong family history of coronary heart disease, or with certain cutaneous stigmata of hyperlipoproteinaemia and when fasting serum samples are seen to be lipaemic. Family studies should be performed in appropriate cases to identify relatives at increased risk of developing coronary heart disease. Patients with conditions known to cause secondary hyperlipoproteinaemia should be investigated if they fall into one of these categories but only after treatment of the underlying condition. Non-specialist laboratories should be able to measure total cholesterol and triglyceride concentrations and high density lipoprotein cholesterol concentrations. Lipoprotein electrophoresis has a limited role in such laboratories and is not necessary as a routine procedure. Specialist laboratories should in addition be able to measure individual lipoproteins and identify apolipoprotein E phenotypes.     

Sickness and Healing: An Anthropological Perspective

Sickness and Healing: An Anthropological Perspective. Robert A. Hahn. New Haven, CT: Yale University Press, 1995 (cloth and paper), viii. 327 pp.     

Ultrastructure of type-I salivary-gland acini in four species of ticks and the influence of hydration states on the type-I acini ofAmblyomma americanum

We describe the ultrastructure of type-I salivary-gland acini in two argasid and two ixodid species. The basic cell types in the agranular or type-I acini, and their associations, are very similar in argasids and ixodids; therefore, we propose an anatomical nomenclature for cells in the type-I acinus based on the adult ixodidsAmblyomma americanum andDermacentor variabilis, and the argasid adultArgas (Persicargas) arboreus and on nymphalOrnithodoros moubata. Four cell types were present in all specimens: one central lamellate cell, a variable number of peripheral lamellate cells, a variable number of peritubular cells depending on the species, and one circumlumenal cell. The lamellate cells had infolded basal plasma membranes that presented an amplified surface area to the hemolymph. These cells most likely secreted the fluid involved in water vapor uptake by ticks. ForAmblyomma americanum females, abundant K⁺-dependent, ouabain-sensitive Na⁺, K⁺-ATPase complexes were located on the infolded basal plasma membranes of the lamellate cells. Apical membranes of the lamellate cells, and plasma membranes of other cell types in the acinus had little or no evidence of Na⁺, K⁺-ATPase activity. Only the central lamellate cell extended from the hemolymph of the acinus to its lumen; peripheral cells did not contact the lumen. Except when the ticks were rehydrating, lipid inclusions were common features in the lamellate cells of the ixodids. Lipid inclusions were not seen in argasid type I acini; however, glycogen deposits were common. To determine if acinar cells respond to the changing hydration state of the tick, unfed femaleA. americanum were subjected to dehydration/rehydrating conditions. During rehydration, mitochondria in the lamellate cells changed from a matrix of medium electron-density and intermembrane space (orthodox configuration) to a matrix of greater density and larger intermembrane space (condensed configuration). The orthodox configuration was consistently observed in control and dehydrating ticks. The condensed configuration was the norm for mitochondria in lamellate cells of rehydrating ticks. Lipid inclusions were depleted in the rehydrating ticks compared to control or dehydrating ticks. Acini appeared to be reverting to the control or desiccated state when ticks were returned to low humidity, suggesting that these changes were cyclical. Nymphs ofO. moubata subjected to the same dehydration/rehydrating conditions showed no obvious ultrastructural changes.