A comparison of Peronospora parasitica (Downy mildew) isolates from Arabidopsis thaliana and Brassica oleracea using amplified fragment length polymorphism and internal transcribed spacer 1 sequence analyses.

Amplified fragment length polymorphism (AFLP) fingerprints and internal transcribed spacer 1 (ITS1) sequences from 27 Peronospora parasitica isolates (collected from Arabidopsis thaliana or Brassica oleracea), 5 Albugo candida isolates (from the same hosts and from Capsella bursa-pastoris), and 1 Bremia lactucae isolate (from Lactuca sativa) were compared. The AFLP analysis divided the isolates into five groups that correlated with taxonomic species and, in most cases, with host origin. The only exception was a group consisting of A. candida isolates from both B. oleracea and C. bursa-pastoris. ITS1 sequence analysis divided the isolates into the same five groups, demonstrated the divergence between P. parasitica isolates from A. thaliana and B. oleracea, and, using previously published ITS1 sequences, clearly showed the relationship between A. candida isolates from different hosts.

Efficacy of MGI 114 (HMAF) against the MRP+ metastatic MV522 lung carcinoma xenograft.

This study is part of an effort to evaluate efficacy of the novel agent MGI 114 (HMAF) against tumors resistant to conventional chemotherapeutic agents. MGI 114 is a novel semisynthetic anticancer agent currently in chemotherapeutic phase II trials to evaluate activity against various solid tumors. Previous studies indicate MGI 114 was active against human MDR1/gp170+ solid tumor xenografts. Recent evidence suggests overexpression of the MRP protein may also be clinically relevant to development of drug resistance in solid tumors. We evaluated the efficacy of MGI 114 against a human MRP+ lung carcinoma xenograft. Parent MV522 lung carcinoma cells were transfected with a MRP cDNA expression vector and resistant cells selected by exposure to vinblastine (30-fold resistance). Analysis of resistant clones indicated 20- to 40-fold increases in expression of both MRP mRNA and MRP protein. Administration of MGI 114 at the maximum tolerated dose (7 mg/kg, 5 x/week for 3 weeks) to MRP tumor-bearing mice demonstrated this novel agent was active against MRP+ tumors and significantly extended their lifespan (p<0.001). In contrast, other cytotoxic agents had minimal activity against this MRP+ xenograft. These results indicate MGI 114 should retain activity in vivo against MRP+ tumor types. The development of this MRP+ xenograft model, in conjunction with the parent MV522 and MDR1/gp170+ xenograft models, will be useful for screening new classes of agents for activity against multidrug-resistant tumors.

Natural allelic variation identifies new genes in the Arabidopsis circadian system.

We have analysed the circadian rhythm of Arabidopsis thaliana leaf movements in the accession Cvi from the Cape Verde Islands, and in the commonly used laboratory strains Columbia (Col) and Landsberg (erecta) (Ler), which originated in Northern Europe. The parental lines have similar rhythmic periods, but the progeny of crosses among them reveal extensive variation for this trait. An analysis of 48 Ler/Cvi recombinant inbred lines (RILs) and a further 30 Ler/Col RILs allowed us to locate four putative quantitative trait loci (QTLs) that control the period of the circadian clock. Near-isogenic lines (NILs) that contain a QTL in a small, defined chromo- somal region allowed us to confirm the phenotypic effect and to map the positions of three period QTLs, designated ESPRESSO, NON TROPPO and RALENTANDO. Quantitative trait loci at the locations of RALENTANDO and of a fourth QTL, ANDANTE, were identified in both Ler/Cvi and Ler/Col RIL populations. Some QTLs for circadian period are closely linked to loci that control flowering time, including FLC. We show that flc mutations shorten the circadian period such that the known allelic variation in the MADS-box gene FLC can account for the ANDANTE QTL. The QTLs ESPRESSO and RALENTANDO identify new genes that regulate the Arabidopsis circadian system in nature, one of which may be the flowering-time gene GIGANTEA.

Constraints on mutability in a multiallelic gene family.

A highly variable family of related DNA sequences was examined in order to determine the effect of local sequence environment on substitution mutation; 29 sequences from the Brassica self-incompatibility gene family, which possess a high level of nonsynonymous mutations, were aligned and grouped according to their similarity and function. The level and distribution of substitution mutations were calculated. A nonrandom distribution of sequence variation was observed along the sequences. The effect of neighbor biases and structural and thermodynamic measures were then compared in the absence of strong codon conservation. Biases were observed in the rates of substitution of the same base pair in different local sequence environments. The effect of the 5' neighbor was such that nucleotide A or C was associated with more mutations than G or T. There were significant interactions of certain dinucleotides with the frequency of mutation. Sequence-dependent measures of helical stability, intrinsic curvature, components of curvature, and stacking interactions were calculated for each sequence. Decreased helical stability was found to be associated with increased mutation. The compound measure of curvature, calculated according to the "wedge" model, showed little association with mutation. However, the components of increased wedge angle and decreased twist both showed an association with increased mutation. A small effect of A-type DNA stacking was found to be associated with mutated bases.

Early clinical experience with the Baerveldt 350-mm2 glaucoma implant and associated extraocular muscle imbalance.

PURPOSE: The Baerveldt glaucoma implant is a new commercially available aqueous drainage device. Clinical data on the performance of the implant are relatively limited. The purpose of this investigation is to explore potential advantages and disadvantages of this implant over the more widely used Molteno implant. METHODS: Retrospective analysis was performed on 37 eyes of 36 patients with refractory glaucoma who underwent placement of a mid-sized Baerveldt 350-mm2 implant. Patient selection was based on previous failure of conventional medical, laser, and surgical management, with poor prognosis for further glaucoma surgery and adjunctive antifibrosis therapy. RESULTS: Significant postoperative extraocular motility restriction and heterotropia were found in the operated eyes. Twenty-three (77%) of 30 eyes measured have significant heterotropia in primary gaze and restriction of gaze into the quadrant of the implant. As a result, 11 (65%) of 17 functionally binocular patients have diplopia in primary gaze. CONCLUSIONS: Pending further study, the authors are avoiding placement of the Baerveldt 350-mm2 implant in both binocular and monocular patients due to the high frequency of induced heterotropia and motility restriction.

The use of Molteno implant and anterior chamber tube shunt to encircling band for the treatment of glaucoma in keratoplasty patients.

This retrospective study reviews the results of 35 keratoplasty patients with complex corneal and glaucoma disease, who received Molteno-type (n = 25) or anterior chamber tube shunt to encircling band (ACTSEB)-type (n = 10) implant for the treatment of difficult glaucomas. The implant was placed before the keratoplasty in 14 eyes, during the keratoplasty procedure in 6 eyes, and subsequent to the corneal surgery in 15 eyes. Mean follow-up for the keratoplasty was 25.46 months (range, 6-58 months) and 24.74 months (range, 7-42 months) for the seton procedure. Graft rejection occurred in 12 (34%) of 35 eyes and was progressive in 9 eyes. Nonimmunologic failure was seen in 9 (26%) of 35 eyes. Grafts were repeated in ten eyes with eight of these (80%) remaining clear at a mean of 14.4 months. Considering the results of the repeat grafts, 25 (71%) of 35 eyes achieved clear transplants. Overall, 46% of patients had final visual acuities of 20/100 or better and 69% had final visual acuities of 20/400 or better. The mean preoperative intraocular pressure (IOP) of 34.54 mmHg (range, 14-68 mmHg; standard deviation [SD], 11.51) was lowered to a mean of 14.65 mmHg (range, 6-30 mmHg; SD, 4.49). In the final analysis, 30 (86%) of 35 eyes were judged successful from a glaucoma standpoint. We conclude that the Molteno- and ACTSEB-type implants are viable treatment alternatives in this difficult glaucoma group.

A new technique for the surgical repair of cyclodialysis induced hypotony.

A new technique for the treatment of cyclodialysis induced hypotony is presented along with the results achieved in 4 cases. The technique is best suited to large clefts, or those in which conservative therapy has failed. No serious sequelae resulting from the procedure were noted in any of our cases.