Potent in vitro inhibition of thymidylate synthase (5,lO-methylenetetrahydrofolate:dUMP C-methyltransferase, EC 2.1.1.45) by 5-fluoro-2'-deoxyuridylate requires 5,10-methylenetetrahydrofolate. The cytotoxicity of 5-fluoro-2'-deoxyuridine towards cultured L1210 mouse leukemia cells is reduced when intracellular reduced folates are depleted, either by limiting the source in media or by inhibition of dihydrofolate reductase with methotrexate. Likewise, the intracellular amount of 5-fluoro-2'-deoxyuridylate covalently bound to thymidylate synthase in L1210 cells treated with 5-fluoro-2'-deoxyuridine is greatly diminished when cells are depleted of folate cofactors. The folate requirement for optimal growth of L1210 cells is lower than that required for maximal cytotoxicity of 5-fluoro-2'-deoxyuridine. These findings provide a biochemical rationale that may be useful in designing clinical protocols that use 5-fluorinated uracil analogs. bursts. The suspensions were heated at 1000 for 90 sec and 50-Al (ca 0.4 mg of protein) samples were electrophoresed on slab gels of 12% polyacrylamide containing 0.1% NaDodSO4 (9, 10). The gel tracts were sliced into seventeen 0.5-cm fractions, each of which was incubated in 1 ml of NCS (Amersham/Searle Co.) at 60°overnight and assayed for radioactivity in a liquid scintillation system.

Many sources of dissatisfaction with care among persons with life-threatening illness and their families are interpersonal in nature. The physician's respectful presence and demonstration of caring are highly desired, significant interventions for those who cannot be cured of illness and for their loved ones. Making healthcare professionals aware of these concerns may itself bring about some changes in daily practice. Further research is needed to test the most useful skills and behaviors of healthcare professionals in caring for persons with life-threatening illness and their loved ones.

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The postlarval development of gill raker denticles is described for the engrauloid (anchovy) genera Coilia, Lycothrissa, Setipinna, Thryssa, Stolephorus, and Encrasicholina based on scanning electron microscopy. The raker structure of adult Papuengraulis is also described. In the coiliid genera Coilia, Lycothrissa, Setipinna, Thryssa, and Papuengraulis, denticle development is not confined to particular region(s) of the raker. With few exceptions, the proliferation of denticles with growth is greatest along the upper raker edge; denticles are smaller and less dense on the raker faces and along the lower raker edge. Some Thryssa and Setipinna have a derived condition of denticle clustering along the upper raker edge. In Stolephorus and Encrasicholina, denticle development is confined to the upper raker half and includes the development of a single row of denticles along each raker face. A phylogenetic analysis of engrauloid raker structure, incorporating data from Bornbusch ( 88: Copeia 1988:174-182) and based on outgroup comparisons, indicates that for the Engrauloidea: (1) the pattern of denticle development shared by coiliids is plesiomorphic; and (2) the pattern of denticle development shared by Stolephorus, Encrasicholina, and most other engraulids is synapomorphic for the Engraulidae. There is no evidence that the studied coiliids Stolephorus and Encrasicholina are suspension feeders. The engraulid pattern of raker denticle development which is retained in suspension feeding engraulids of the genus Engraulis was thus derived before the derivation of suspension feeding in Engraulis. Comparative morphological and phylogenetic studies of clupeomorph raker structures and feeding behaviors can infer the historical origins of morphology-behavior associations, help define possible directions for analyses of raker denticle function, and thereby help elucidate the significance of structure-function couplings in the evolution of such clupeomorph trophic behaviors as suspension feeding. © 1992 Wiley-Liss, Inc.