Synthesis of methyl pyranosides and furanosides of 3-deoxy-D-manno-oct-2-ulosonic acid (KDO) by acid-catalysed solvolysis of the acetylated derivatives

Treatment of methyl 2,4,5,7,8-penta-O-acetyl-3-deoxy-alpha-D-manno-oct- 2-ulopyranosonic acid, or its methyl ester, with refluxing methanolic 0.1 M hydrogen chloride for 16 h gave 95% of methyl (methyl 3-deoxy-alpha-D-manno-oct-2-ulopyranosid)onate. Acetylation of the methyl ester of 3-deoxy-D-manno-oct-2-ulosonic acid (KDO) gave mainly methyl 2,4,6,7,8-penta-O-acetyl-3-deoxy-alpha,beta-D-manno-oct-2-ulofuranoso nate. Treatment of this mixture with methanolic 0.02 M hydrogen chloride at room temperature gave methyl (methyl 3-deoxy-alpha, beta-D-manno-oct-2-ulofuranosid)onate and the corresponding 4-acetates which were isolated by reverse-phase column chromatography of their 7,8-O-isopropylidene derivatives. Confirmation of the position of the isopropylidene group was obtained by acetylation to give methyl (methyl 4,6-di-O-acetyl-3-deoxy-7,8-O-isopropylidene-alpha,beta-D-manno-oct-2-ul ofuranosid)onate. The furanose anomers were differentiated primarily by J3,4 values (alpha approximately 6.1 Hz, beta approximately 2.2 Hz). The anomeric configuration in the furanose series has been assigned on the basis of optical rotation.     

Establishment of two new multi-drug resistant variants of the human tumor line Hep-2

Two multi-drug resistant variants of the human carcinoma line Hep-2 have been selected by adaptation to progressively increasing concentrations of adriamycin. In comparison to the wild-type Hep-2 cells, the variant lines both showed approximately 100-fold resistance to adriamycin, 10 to 20-fold resistance to the vinca alkaloids but only 2–3 fold resistance to VP-16 and VM-26. There was essentially no difference between wild-type and variant cells in regard to sensitivity to threosulfan and 5-fluorouracil. The drug-resistant phenotype is stable for at least 3 months in the absence of drug, and is partially reversible by concomitant treatment with Verapamil. Chromosomal abnormalities consistent with gene amplification were observed in one of the variant lines. Sensitivity of variant cells to adriamycin was enhanced following trypsin-EDTA treatment.     

Arginase activity and other cellular events associated with epidermal hyperplasia

The unknown biochemical role of arginase in epidermal metabolism was probed by examining the association of elevated arginase activty with epidermal hyperplasia and hyperkeratinization. Epidermal hyperplasia as induced experimentally by topical application of 1-decanol to the right side of male hairless mice while the contralateral side served as control. Arginase activity, incorporation of ³ H-thymidine into DNA, DNA and protein content were measured in the separated control and experimental epidermis six hours and on days 1 through 5 and 7 after 1-decanol application. After six hours, the epidermis appears damaged histologically, and DNA synthesis is inhibited. By day 1, incoporation of ³ H-thymidine into DNA is elevated and a new hyperplastic epidermis has formed beneath the original epidermis. Epidermal arginase is elevated two through seven days after 1-decanol application and always is associated with continuing epidermal hyperplasia. The stimulation of DNA synthesis, which parallels the induction of epidermal hyperplasia by 1-decanol, precedes the induction of epidermal arginase activity. An attempt to relate these results with polyamine synthesis and other metabolic events is made.     

Quantification of avian parental behavior: what are the minimum necessary sample times?

Methods used to study parental behavior are largely idiosyncratic and are rarely tested to verify that they yield reliable data. In particular, the minimum number and duration of observations used to describe behavior accurately is rarely, if ever, justified. Using data on parental behavior of Eastern Kingbirds (Tyrannus tyrannus) collected by video in Oregon, we evaluated three questions regarding sampling methods: (1) Is within‐pair behavior sufficiently consistent among days so that observations from a single session are representative of parental behavior? (2) Does a 1‐h sampling window fairly represent parental behavior or is a longer period needed to accurately describe behavior? (3) Assuming that a 1‐h period is sufficient, does the first hour immediately after disturbance to start recordings yield reliable data? We found that among‐pair differences in parental behavior were consistent over different days and that a single hour of observation was representative of parental behavior over a longer (2–3 h) period of observation. However, our data also suggested that the first hour yielded less representative data than the remaining 2–3 h; nonetheless, consistent among‐pair differences were still detectable. The shortcoming of data collected in the first hour appeared to be due to a lingering effect of human disturbance from setting up recording devices rather than a time‐of‐day effect. We suggest that researchers test the appropriateness of their methods, but our kingbird data suggest that observations over relatively brief periods can yield useful and reliable data.