Pterygium recurrence following preoperative topical Mitomycin C and 5-Fluorouracil eyedrops.

INTRODUCTION: Various adjuvant therapies have been used to prevent recurrence after pterygium excision. However, no single agent has been proven to be a gold standard for completely preventing recurrence with no associated complications. PURPOSE: This study aims to compare the recurrence rate following preoperative topical mitomycin C (MMC) and 5-fluorouracil (5-FU) eye drops in pterygium excision surgery. METHODS: In this interventional longitudinal comparative study, 90 patients with primary pterygium attending the Ophthalmology Clinic were enrolled and randomized into three equal groups of 30 each. Groups A, B, and C received preoperative 0.02% MMC eye drops, 1% 5-FU eyedrops, and placebo treatment respectively for one week before surgery followed by pterygium excision with conjunctival autograft and histopathological analysis. Patients were followed for 6months to identify recurrence. RESULTS: At the end of the 6months, the recurrence rate in the preoperative MMC group (6.7%) was less than the 5-FU (13.3%) and placebo (20%) groups. The histopathological findings were consistent with pterygium tissues. There were high grades of inflammation, degeneration, and vascularization in both the MMC and 5-FU groups in the specimens which recurred within a period of 6months. Five patients had a novel finding of smooth muscle choristoma tissue with bundles of smooth muscle cells and fat cells clustered among the conjunctival tissue. CONCLUSION: Based on our study results, we demonstrate that preoperative topical MMC and 5-FU eyedrops have efficacy in reducing recurrence in pterygium surgeries. The eyedrop route of administration has been proven to be an effective and easier alternative, enabling us to monitor for adverse effects of adjuvant drugs. Histopathological evaluation provides indices to predict features of future recurrence in pterygium specimens. This is the first study in which the efficacy of preoperative MMC and 5-FU is studied in eyedrop formulation along with histopathological correlation with recurrence.

TSC1 and TSC2 mutations in patients with lymphangioleiomyomatosis and tuberous sclerosis complex.

BACKGROUND: Lymphangioleiomyomatosis (LAM) is a prominent finding in the setting of tuberous sclerosis complex (TSC). OBJECTIVE: The present study was designed to compare cystic lung changes consistent with LAM in patients with a TSC1 disease-causing mutation, TSC2 disease-causing mutation, or no mutation identified (NMI). METHODS AND RESULTS: We conducted a retrospective review of the chest computed tomography (CT) of 45 female and 20 male patients with TSC and found cysts consistent with LAM in 22 (49%) women and two (10%) men. In the female population, changes consistent with LAM were observed in six of 15 (40%) patients with TSC1, 11 of 23 (48%) with TSC2, and five of seven (71%) with NMI. While the predominant size of cysts did not differ across these three groups, TSC2 women with LAM had a significantly greater number of cysts than did TSC1 patients (p = 0.010). CONCLUSIONS: These findings suggest a higher rate of LAM in TSC1 than previously recognised, as well as a fundamental difference in CT presentation between TSC1 and TSC2.

Molecular characterization and distribution of a 145-bp tandem repeat family in the genus Populus.

This report aims to describe the identification and molecular characterization of a 145-bp tandem repeat family that accounts for nearly 1.5% of the Populus genome. Three members of this repeat family were cloned and sequenced from Populus deltoides and P. ciliata. The dimers of the repeat were sequenced in order to confirm the head-to-tail organization of the repeat. Hybridization-based analysis using the 145-bp tandem repeat as a probe on genomic DNA gave rise to ladder patterns which were identified to be a result of methylation and (or) sequence heterogeneity. Analysis of the methylation pattern of the repeat family using methylation-sensitive isoschizomers revealed variable methylation of the C residues and lack of methylation of the A residues. Sequence comparisons between the monomers revealed a high degree of sequence divergence that ranged between 6% and 11% in P. deltoides and between 4.2% and 8.3% in P. ciliata. This indicated the presence of sub-families within the 145-bp tandem family of repeats. Divergence was mainly due to the accumulation of point mutations and was concentrated in the central region of the repeat. The 145-bp tandem repeat family did not show significant homology to known tandem repeats from plants. A short stretch of 36 bp was found to show homology of 66.7% to a centromeric repeat from Chironomus plumosus. Dot-blot analysis and Southern hybridization data revealed the presence of the repeat family in 13 of the 14 Populus species examined. The absence of the 145-bp repeat from P. euphratica suggested that this species is relatively distant from other members of the genus, which correlates with taxonomic classifications. The widespread occurrence of the tandem family in the genus indicated that this family may be of ancient origin.

Mutational analysis of conserved nucleotides in a self-splicing group I intron.

We have constructed all single base substitutions in almost all of the highly conserved residues of the Tetrahymena self-splicing intron. Mutation of highly conserved residues almost invariably leads to loss of enzymatic activity. In many cases, activity could be regained by making additional mutations that restored predicted base-pairings; these second site suppressors in general confirm the secondary structure derived from phylogenetic data. At several positions, our suppression data can be most readily explained by assuming non-Watson-Crick base-pairings. In addition to the requirements imposed by the secondary structure, the sequence of the intron is constrained by "negative interactions", the exclusion of particular nucleotide sequences that would form undesirable secondary structures. A comparison of genetic and phylogenetic data suggests sites that may be involved in tertiary structural interactions.

Stereochemical course of catalysis by the Tetrahymena ribozyme.

The group I intron from Tetrahymena catalyzes phosphodiester transfer reactions on various RNA substrates. A modified RNA substrate with a phosphorothioate group in one stereoisomeric form at the site of reaction was synthesized in order to determine the stereochemical course of an RNA-catalyzed reaction. The reaction product was digested with a stereospecific nuclease to determine the configuration of the product phosphorothioate. The reaction occurs with inversion of configuration at phosphorus, implying an in-line pathway for the reaction.