Partial preparative purification of leptine I from foliage of the wild potato, Solanum chacoense (Bitt.).

Leptine I, a glycoalkaloid only known to occur in the foliage of the wild potato species Solanum chacoense (Bitt.), is a potent feeding deterrent to the economically serious insect pest, the Colorado potato beetle (Leptinotarsa decemlineata Say). In order to demonstrate, systematically, the effectiveness of leptine I, incorporation into synthetic beetle diet trials is necessary. We describe a preparative procedure for the partial purification of leptine I by a series of steps, starting with a solid-phase C18 extraction, followed by sequential silica gel chromatography, and finally reversed-phase preparative HPLC. This preparation yields a white powder, containing leptine I as the sole glycoalkaloid, with an overall purity of greater than 65%, and is entirely suitable for incorporation into synthetic diets.

Congenital diaphragmatic hernia. Epidemiology and outcome.

Congenital diaphragmatic hernia is a relatively common birth defect. It affects about 1114 babies a year in the United States. Reported survival averages 60% but may be significantly lower. We do not understand the etiology of CDH. Its association with other anomalies and several distinct patterns of presentation suggest that more than one cause may exist. There is a high degree of variability in both treatment and outcomes, but no data exist to allow a rigorous comparison of the efficacy of various treatment strategies. Stratification of patients into more homogeneous groups will be a necessary prerequisite for the design of meaningful comparative trials. The incidence of the lesion prevents any single institution from accruing sufficient patients to conduct such a trial. An ad hoc multicenter study group (the Congenital Diaphragmatic Hernia Study Group) has been formed for this purpose. This organization has begun collecting data with an initial goal of developing a stratification scheme. Prospective data collection should allow verification of several of the estimates made in this article. Current data make it clear that CDH represents a major cause of perinatal morbidity and mortality.

Bioassays of segregating plants : A strategy for studying chemical defenses.

Solanum chacoense is a wild potato species resistant to the Colorado potato beetle,Leptinotarsa decemlineata. Most genotypes ofS. chacoense synthesize the glycoalkaloids solanine (sol) and chaconine (chac) and are hosts of the beetle. A few rare genotypes have a gene(s) for acetylation of carbon-23 of the steroid aglycone of sol and chac. Laboratory bioassays and replicated field tests of clones differing in the presence or absence of the acetyl moiety showed that acetylation of sol and chac markedly affects the response of both adults and larvae to the foliage. Adult feeding deterrency conferred by acetylated forms of sol and chac (leptines) in leaf-disk preference tests was consistent with the degree of antixenosis measured in the field. Development of larvae on foliage of clones with leptines was also inhibited. The studies support the validity of using laboratory bioassays of plants segregating for levels of a suspected defense compound to determine the role the compound has in defending the plant from attack by an insect predator in the field.