Search

Abdominal lymphovascular malformations (ALMs) are rare cystic masses that can present with nonspecific symptoms. We present a case of a 7-month-old boy who, during an uncomplicated communicating hydrocele repair, was found to have an incidental large, prolapsed mesenteric abdominal lymphovascular malformation. The case serves to highlight the variability in presentation and natural history of ALMs, and the ease with which they can be disguised by more common pathology. We further underscore the importance of individualized therapy with regards to ALMs, emphasized by our course of active surveillance allowing our patient to avoid ionizing radiation and additional surgical intervention.

The Hsp90 molecular chaperone has been implicated as a contributor to evolution in several organisms by revealing cryptic variation that can yield dramatic phenotypes when the chaperone is diverted from its normal functions by environmental stress. In addition, as a cancer drug target, Hsp90 inhibition has been documented to sensitize cells to DNA-damaging agents, suggesting a function for Hsp90 in DNA repair. Here we explore the potential role of Hsp90 in modulating the stability of nucleotide repeats, which in a number of species, including humans, exert subtle and quantitative consequences for protein function, morphological and behavioral traits, and disease. We report that impairment of Hsp90 in human cells induces contractions of CAG repeat tracks by tenfold. Inhibition of the recombinase Rad51, a downstream target of Hsp90, induces a comparable increase in repeat instability, suggesting that Hsp90-enabled homologous recombination normally functions to stabilize CAG repeat tracts. By contrast, Hsp90 inhibition does not increase the rate of gene-inactivating point mutations. The capacity of Hsp90 to modulate repeat-tract lengths suggests that the chaperone, in addition to exposing cryptic variation, might facilitate the expression of new phenotypes through induction of novel genetic variation.

A reporter gene system that allows in situ detection of cells that have suffered a specific frameshift mutation was developed. To construct the reporter gene, the open reading frame of a human placental alkaline phosphatase (PLAP) gene was disrupted by insertion of either 5 or 7 G:C basepairs, which formed mutant alleles carrying 9 and 11 consecutive G residues, respectively. The mutant PLAP genes did not produce alkaline phosphatase activity in cultured mouse cells in transient transfection assays. Several cell lines that contained integrated copies of the mutant PLAP genes were made. Histochemical staining of fixed cells showed that these cell lines contained a small number of cells that expressed PLAP activity and bound antibodies directed against PLAP. Cells carrying the allele with 11 consecutive G residues (G11 allele) acquired PLAP activity at a rate between 2 x 10(-3) and 2 x 10(-4) events per cell per generation, depending on the cell line. Cells carrying the allele with 9 consecutive G residues (G09 allele) acquired PLAP activity at a rate between 2 x 10(-5) and 2 x 10(-6) events per cell per generation, depending on the cell line. Cultures of PLAP+ cells were derived from cell lines carrying PLAP mutant genes. All the cells in these cultures had PLAP activity and bound anti-PLAP antibody. PLAP mRNA levels were the same in cultures where all cells were PLAP+ and in cultures where less than 1% of the cells expressed PLAP activity. DNA sequence analysis of PLAP+ cells showed that the G11 allele reverted by losing one basepair, and the G09 allele reverted by gaining one basepair.

A sensitive, selective reversed phase-high performance liquid chromatographic (HPLC) assay that uses UV detection has been developed for etoposide (4'-demethylepipodophyllotoxin 9-[4,6-O-(R)-ethylidene-beta-D-glucopyranoside) 1. Parent drug is separated from its known metabolites, the cis-picrolactone 2, the hydroxy derivative 3, and the aglycone 4. After the addition of the internal standard (teniposide, 5) to 0.5 mL of plasma, 3 mL of chloroform is added and the sample is centrifuged. The lower organic layer is removed, evaporated in a stream of nitrogen, and reconstituted with 500 microL of mobile phase prior to injection. A phenyl mu Bondapak column (30 cm X 4 mm) and a mobile phase, consisting of 10 microM ammonium acetate (pH 5.5) in methanol:water:acetonitrile (50:45:5), were used to separate the compounds. The flow rate was 2 mL/min. Detection was achieved with a UV monitor set at 230 nm. The aglycone 4, etoposide (1), cis-picrolactone 2, and teniposide (5) had retention times of 3, 4, 4.8, and 9 min, respectively. The extraction efficiency of etoposide ranged from 88 to 94% with a coefficient of variation of 12% at 0.8 micrograms/mL and 4% at 28 micrograms/mL. This assay has an intraday and interday coefficient of variation of 6%, quantitates etoposide at concentrations as low as 0.4 micrograms/mL, and separates etoposide from its known metabolites. The procedure described represents an alternative to a previously published assay that also separated etoposide from its metabolites, but used electrochemical detection.