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Purpose: To determine the penetration of orally administered trimethoprim (TMP)-sulfamethoxazole (SMX) into the aqueous and vitreous cavity of noninflamed human eyes., Methods: Nine adult patients undergoing cataract surgery and 10 adult patients undergoing pars plana vitrectomy were given 3 doses of oral TMP-SMX every 12 hours before the surgery. Aqueous and blood samples were collected from patients undergoing cataract surgery; vitreous and blood samples were collected from patients undergoing vitrectomy. The levels of TMP and SMX were analyzed using high-performance liquid chromatography and were compared with the mean minimum inhibitory concentrations (MIC) of potential ocular pathogens., Results: TMP-SMX was present in all samples. Among eyes undergoing cataract surgery, the mean concentrations of TMP in aqueous and blood were 0.341 ± 0.141 μg/mL (mean ± SD) and 1.501 ± 0.433 μg/mL and of SMX were 5.259 ± 0.929 μg/mL and 11.835 ± 2.100 μg/mL, respectively. Among eyes undergoing vitrectomy, the mean concentrations of TMP in vitreous and blood were 1.864 ± 0.807 μg/mL and 4.591 ± 2.979 μg/mL and of SMX were 5.910 ± 2.705 μg/mL and 39.289 ± 15.469 μg/mL, respectively. MIC levels were achieved against many bacterial pathogens, including methicillin-resistant Staphylococcus aureus., Conclusions: TMP-SMX penetrates both the aqueous and vitreous cavities when given orally. The components reach therapeutic inhibitory concentrations in the ocular cavity against many potential pathogens.

Purpose: To evaluate the efficacy of adding either linezolid or daptomycin to Optisol-GS donor storage medium in reducing methicillin-resistant Staphylococcus aureus (MRSA) contamination of donor corneas., Methods: Optisol-GS was supplemented with either linezolid at 2×, 4×, or 10× minimum inhibitory concentration (MIC) or daptomycin and calcium at 5× or 50× MIC. Unsupplemented control groups were also used. Gentamicin-sensitive and gentamicin-resistant isolates of MRSA were added, and vials were refrigerated for 48 hours followed by sampling for viable colony counts immediately upon removal from refrigeration and after warming to room temperature for 3 hours. Safety studies of Optisol-GS supplemented with 50× MIC daptomycin and calcium were performed by evaluating the central corneal thickness and endothelial cell density of the donor cornea. Stability of daptomycin in Optisol-GS at storage was also tested., Results: No added benefit was observed with linezolid supplementation to Optisol-GS against gentamicin-sensitive MRSA, with reduction in viable colony counts by >90% in all groups. No benefit was observed with linezolid supplementation against gentamicin-resistant MRSA, with the majority of inocula remaining viable in all groups. Viable counts of gentamicin-sensitive MRSA and gentamicin-resistant MRSA were effectively reduced with both 5× MIC and 50× MIC daptomycin supplementation. 50× MIC daptomycin-supplemented Optisol-GS had no appreciable effect on the central corneal thickness or endothelial cell density of the donor cornea and was stable at storage for 14 days., Conclusions: The addition of daptomycin to Optisol-GS significantly increases the anti-MRSA activity of the medium without any apparent negative effects on donor corneal tissue.

Purpose: To compare the incidence of flap complications after creation of laser in situ keratomileusis (LASIK) flaps using a zero-compression microkeratome or a femtosecond laser., Setting: John A. Moran Eye Center, Department of Ophthalmology, University of Utah, Salt Lake City, Utah, USA., Design: Evidence-based manuscript., Methods: The flap complication rate was evaluated during the initial 18 months of experience using a zero-compression microkeratome (Hansatome) or a femtosecond laser (IntraLase FS60) for flap creation., Results: The flap complication rate was 14.2% in the microkeratome group and 15.2% in the femtosecond laser group (P = .5437). The intraoperative flap complication rate was 5.3% and 2.9%, respectively (P = .0111), and the postoperative flap complication rate, 8.9% and 12.3%, respectively (P = .0201). The most common intraoperative complication in the microkeratome group was major epithelial defect/sloughing; the rate (2.6%) was statistically significantly higher than in the femtosecond laser group (P = .0006). The most common postoperative complication in both groups was diffuse lamellar keratitis (DLK) (6.0%, microkeratome; 10.6%, femtosecond laser) (P = .0002)., Conclusion: Although the total complication rates between the 2 groups were similar, the microkeratome group had significantly more epithelial defects intraoperatively and the femtosecond laser group had significantly more DLK cases postoperatively., (Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To determine the relationship between the achieved refractive change and the change in simulated keratometry (K) after myopic laser situ keratomileusis (LASIK) and compare this relationship between custom and conventional treatments., Setting: Department of Ophthalmology, University of California, Davis, Sacramento, California, and John A. Moran Eye Center, Salt Lake City, Utah, USA., Methods: The change in simulated K and the refractive change induced by custom myopic LASIK and conventional LASIK were determined. The relationship between the variables was analyzed by regression methods., Results: Custom treatment was performed in 106 eyes and conventional treatment in 224 eyes. Simple linear regression analysis did not fit the clinical observation when the refractive change was less than 2.00 diopters (D) of myopic correction with both treatments. Under the linear model and nonlinear model, each unit of refractive change yielded a greater change in corneal topographic power with custom treatment than with conventional treatment. With both treatments, the rate of change in simulated K was not constant and was much more variable with lower amounts of correction. The relationship was more constant and linear with larger amounts of refractive correction., Conclusions: The relationship between the measured change in simulated K and the induced refractive change better fit a nonlinear relationship with smaller amounts of refractive correction in custom LASIK and conventional LASIK. Under all forms of analysis, custom treatments yielded a greater per-unit change in corneal curvature than conventional treatments, especially for refractive corrections of 4.00 D and higher., (Copyright (c) 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Cataract surgery after corneal refractive surgery can be challenging for the ocular surgeon due to the difficulty with accurate intraocular lens (IOL) power determination and unexpected refractive surprises. As clinicians have done more work, a number of error sources have been determined. Furthermore, an increasing number of methods to avoid these refractive surprises have been proposed. The combination of this work has resulted in recommendations for the modification of standard IOL power calculations to improve outcomes. The following article includes a brief on, and by no means, inclusive, error sources and ways to compensate for them.

Purpose: We are reporting a case of bilateral corneal melt after photorefractive keratectomy requiring bilateral corneal transplantations., Results: A 35-year-old man underwent uncomplicated photorefractive keratectomy and was treated postoperatively with topical nepafenac, one drop in both eyes every 2 hours. Three days into this course of treatment, the patient developed bilateral irritation and the dose was decreased to one drop every 4 hours. The next day, he developed stromal melting in both eyes. Although nepafenac was discontinued at this point, the ulcerative keratolysis progressed in both eyes requiring penetrating keratoplasty., Conclusions: We report a case of sterile ulceration after photorefractive keratectomy surgery, which we believe was caused by frequent postoperative dosing of nepafenac.

Objective: To estimate the rate of acute postoperative endophthalmitis after uncomplicated cataract surgery in patients treated before and after surgery with 1 of 2 different fourth-generation fluoroquinolone ophthalmic drops for surgical prophylaxis., Design: Retrospective, multicenter, observational case series., Participants: Included in this study were 20,013 patients from 9 cataract surgery centers in 7 states in the United States., Methods: Patients who had undergone uncomplicated phacoemulsification who received preoperative and postoperative topical fourth-generation fluoroquinolones for surgical prophylaxis between March 2003 and July 2005 were included in the study. The files of patients in whom acute endophthalmitis developed were reviewed and analyzed., Main Outcome Measures: Number and rate of endophthalmitis cases after uncomplicated cataract surgery., Results: During the study period, the participating surgeons performed 20,013 uncomplicated surgeries. Of these, 16,209 patients (81%) received topical gatifloxacin and 3804 patients (19%) were treated with topical moxifloxacin as antiinfective prophylaxis. A total of 14 patients experienced endophthalmitis. The overall rate of endophthalmitis was 0.07%. There were 9 endophthalmitis patients in the gatifloxacin group and 5 endophthalmitis patients in the moxifloxacin group. The rate of endophthalmitis in the gatifloxacin group was 0.06% and the rate in the moxifloxacin group was 0.1%. The difference in the rate of endophthalmitis between the 2 groups was not statistically significant. In 10 of the patients, vitreous culture results were positive. Coagulase-negative staphylococci, followed by streptococci, species were the most commonly isolated organisms in the culture-positive patients., Conclusions: The overall rate of endophthalmitis after uncomplicated cataract surgery in patients treated with topical fourth-generation fluoroquinolones as antiinfective prophylaxis was 0.07%. This rate was within the range of previously reported rates of endophthalmitis in the literature. The difference in the observed rate of postoperative endophthalmitis in patients treated with moxifloxacin versus gatifloxacin was not statistically significant.

Purpose: To retrospectively review the occurrence, treatment, and visual outcomes associated with various etiologies of keratitis as a postoperative complication of laser in situ keratomileusis (LASIK) at an academic surgical center., Setting: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA., Methods: The charts of 5618 post-LASIK patients (10 477 eyes) were reviewed for the development of keratitis. Occurrence rates, management regimens, and final best spectacle-corrected visual acuity (BSCVA) were reported for infectious and noninfectious keratitis etiologies., Results: Post-LASIK keratitis was diagnosed in 279 eyes. The keratitis was diagnosed as infectious in 33 eyes (12%) and as noninfectious in 246 eyes (88%). Infectious cases included 5 eyes (15%) with herpes simplex keratitis (HSV), 18 (55%) with adenoviral keratitis, and 10 (30%) with nonviral (including bacterial, fungal, and parasitic) keratitis. Of noninfectious cases, 193 (78%) were classified as diffuse lamellar keratitis (DLK), 36 (15%) as staphylococcal marginal hypersensitivity, and 17 (15%) as localized debris-related keratitis., Conclusions: The occurrence of post-LASIK keratitis was 2.66%, with DLK being the most common diagnosis overall. The occurrence of noninfectious keratitis (2.34%) was 7.5 times greater than the occurrence of infectious keratitis (0.31%). Adenoviral keratitis had the best visual outcomes overall, with all 18 patients achieving 20/20 BSCVA. In contrast, all 5 eyes with HSV keratitis lost 1 or 2 lines of BSCVA. Excluding adenoviral keratitis, infectious etiologies had significantly worse visual outcomes than noninfectious etiologies at the 20/40 and 20/20 levels (P = .0013 and P<.001, respectively).

Purpose: To describe a case of infectious scleritis caused by methicillin-resistant Staphylococcus aureus (MRSA) after pars plana vitrectomy despite treatment with topical fourth-generation fluoroquinolones., Methods: Single interventional case report., Results: A 72-year-old man presented with scleral thinning and subconjunctival abscess 1 month after pars plana vitrectomy. Microbiological studies including cultures and antibiotic sensitivity were performed. Culture of the scleral abscess showed growth of MRSA resistant to fourth-generation fluoroquinolones and sensitive to vancomycin and erythromycin. Treatment with a combination of topical vancomycin and systemic erythromycin for 6 weeks resolved the infectious scleritis., Conclusions: MRSA can be a cause of infectious scleritis after ocular surgery without a clear source despite surgical prophylaxis with topical fourth-generation fluoroquinolones.

We report the first 2 cases of bacterial keratitis resistant to fourth-generation fluoroquinolones after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). The first patient had Pseudomonas aeruginosa keratitis after PRK despite treatment with moxifloxacin. The second patient was on gatifloxacin post-LASIK when she had methicillin-resistant Staphylococcus aureus (MRSA) keratitis diagnosed. In both cases, culture susceptibilities showed isolates resistant to moxifloxacin and gatifloxacin, and treatment with topical aminoglycosides and surgical intervention was necessary to effect a cure. These cases show the potential limitations in the coverage of these antibiotics.

Purpose: To report 1-year results of laser in situ keratomileusis (LASIK) in 7 eyes with corneal endothelial guttata and a family history of Fuchs' endothelial dystrophy., Setting: John Moran Eye Center, University of Utah, Salt Lake City, Utah, USA., Methods: A retrospective chart review was performed of 4 patients (7 eyes) who had trace to 1+endothelial guttata and a family history of Fuchs dystrophy and then had uneventful LASIK for the correction of myopia and myopic astigmatism. Preoperative and postoperative measurements included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), corneal pachymetry, endothelial cell density (ECD), manifest refraction, and spherical equivalent. The changes in ECD, pachymetry, and spherical equivalent after LASIK were subjected to statistical analysis using a paired Student t test to determine significance., Results: Transient corneal edema was noted in the early postoperative period in 3 eyes of 2 patients. At 1 year, 6 of the 7 (86%) eyes had lost > or =2 lines of BSCVA. A statistically significant decrease in ECD of 12.4% +/- 2.7% was observed at 1 year compared with baseline (P < .001). An increase in corneal thickness (P = .006) and a statistically significant myopic shift in spherical equivalent (P = .017) was also noted at 1 year compared with 3 months., Conclusions: Patients with mild corneal guttata and a family history of Fuchs' dystrophy are prone to transient corneal edema, loss of BSCVA, endothelial cell loss, and myopic regression after uneventful LASIK for correction of myopia and myopic astigmatism.

Purpose: (1) To evaluate the accuracy of nomogram-based adjustment of intraocular lens (IOL) power to achieve a desired refractive target after cataract surgery in postmyopic LASIK and photorefractive keratectomy (PRK) eyes and (2) to compare the accuracy of the nomogram-based method with the clinical history method., Design: Multicenter, retrospective, interventional, noncomparative case series., Subjects: Fourteen patients (19 eyes) after myopic LASIK or PRK with visually significant cataracts., Intervention: All eyes underwent cataract extraction and posterior chamber intraocular lens implantation. In each case, IOL power was determined with standard keratometry and biometry. Power adjustment was made by use of a theoretical nomogram followed by implantation., Main Outcome Measures: (1) Final refraction and spherical equivalent after cataract surgery and (2) deviation of the final spherical equivalent from the refractive target., Results: After cataract extraction, by use of nomogram adjustment, 63.2% of eyes were within 0.5 D of the intended spherical equivalent, 84.2% were within 1.0 diopter of the intended spherical equivalent, and 100% were within 1.5 D of the intended spherical equivalent. The clinical history method was accurate in predicting the correct IOL power in 37.5% of cases, regardless of whether spectacle or corneal plane refraction was used., Conclusions: (1) Given the change in spherical equivalent induced by myopic LASIK/PRK, IOL power can be adjusted accurately to avoid undercorrection without the need for the prerefractive surgery corneal power. (2) The nomogram-based method was more accurate than the clinical history method.

Purpose: To document reversible corneal edema caused by amantadine in a pediatric patient., Methods: A 14-year-old boy with a neurologic tremor was referred for bilateral visual loss. Our examination disclosed bilateral corneal edema without ocular inflammation. Pachymetry confirmed significantly increased corneal thickness above 900 microm., Results: Review of the patient's medical information revealed recent institution of amantadine as a means to control the patient's tremor. On cessation of this agent, rapid resolution of corneal edema and recovery of visual acuity occurred. Repeat pachymetry measurement revealed normal corneal thickness., Conclusion: In cases of corneal edema and in the absence of any identifiable ocular causes, a review of toxic effects of systemic medication should be undertaken. Amantadine can cause corneal decompensation and needs to be considered as part of the differential diagnosis of corneal edema.

Purpose of Review: Keratorefractive procedures designed to decrease refractive errors have gained enormous popularity among ophthalmologists and patients. As the post-refractive surgery patient population ages, visually significant cataracts will develop. With advances in techniques for cataract extraction and intraocular lens implantation, cataract surgery has evolved into a refractive surgical procedure as well as an operation to improve best corrected visual acuity. This raises expectations in terms of desired postoperative refractive status and uncorrected visual acuity. Although performing modern cataract surgery in post-refractive surgery eyes is technically no more complicated than operating on virgin eyes, the calculation of intraocular lens power for a desired refractive target can be challenging and complicated. This has become increasingly apparent as case reports of "refractive surprises" after cataract surgery appear in the literature more frequently., Recent Findings: This paper reviews the current clinical experience with intraocular lens power determination after cataract surgery in post-keratorefractive patients, provides an overview of possible sources of error in intraocular lens power calculation in these patients, and analyzes methods to minimize intraocular lens power errors., Summary: The clinical and routine methods of intraocular lens power determination after keratorefractive surgery need to be modified to improve accuracy. Our knowledge of this subject is still evolving. Given the enormous impact of this problem on clinical practice, awareness of the shortcomings and suggested methods to improve accuracy can be valuable to clinicians.

A 29-year-old African American man presented to the emergency department at the University of Arkansas for Medical Sciences with a fishhook perforating the cornea of the left eye (OS) extending into the anterior chamber. The fishhook was removed via its entrance wound and was subsequently repaired. Fishhook injuries to the eye can result in profound visual impairment. Management of these injuries is dependent on the involved ocular structures and location of the hook. Visual prognosis can be profoundly affected by the initial management. Surgical management options are reviewed.

Purpose: To determine a possible relationship between donor epithelial status on the first postoperative day after keratoplasty and the eventual health of the corneal surface., Methods: We analyzed 91 patients who underwent penetrating corneal transplantation between January 1998 and January 2000, monitoring the epithelial status of the corneas with fluorescein staining using slit-lamp biomicroscopy. Recipient pre- and postoperative variables and donor characteristics were recorded. Macroepithelial defects were classified into three groups according to the extent of the epithelial defect. The results on the first postoperative day were compared with the first and third operative month. Donor and recipient variables were compared with the epithelial status on the first and third month as well., Results: On the first postoperative day, 64.84% of the patients had epithelial defects, 10.99% had defects at the 1-month postoperative visit, and none had defects at the third month. Graft recipients with macroepithelial defects in the first postoperative month were older, had a higher prevalence of blepharitis, higher prevalence of inadequate eye hydration, and slightly increased corneal sensation compared with the group without epithelial defects; however, none of these trends were statistically significant. Patients with macroepithelial defects in the first postoperative month received older donor tissue, and the average preservation-to-surgery time was longer. These donor variables, however, were not significant statistically (p value >0.10) in determining outcome of the epithelial status at the first or third months., Conclusions: Our results suggest that the epithelial status on the first postoperative day is not predictive of surface integrity at 1-month postoperative (p value is 0.2676 for the likehood ratio test). The epithelial status on the first postoperative day is not predictive of the status of the third month after keratoplasty, because none of the 91 patients had epithelial defects after 3 months.

Purpose: (1) To determine the effect of myopic and hyperopic laser in situ keratomileusis (LASIK) on calculation of intraocular lens (IOL) power. (2) To determine a standard way to approach the IOL power determination after LASIK, and (3) To compare different suggested methods., Methods: Biometric analysis and theoretical calculation of IOL powers for eyes undergoing LASIK for myopia and hyperopia were performed., Results: Manual keratometry after LASIK for myopia resulted in underestimation of IOL power. Manual keratometry after hyperopic LASIK resulted in overestimation of IOL power. The amount of error was directly related to the amount of correction by LASIK., Conclusion: The pre-LASIK refraction can be used theoretically to determine an accurate IOL power.

Purpose: To report a 16-year-old woman who had peripheral keratitis as a presenting sign of microscopic polyangiitis (MPA), which rapidly progressed to acute renal failure., Method: Case report., Results: The patient's vasculitis was diagnosed by renal biopsy, which was evaluated with histologic, immunofluorescence, and electron microscopy. The diagnosis was confirmed by laboratory study, which showed a positive antimyeloperoxidase antibody., Conclusion: MPA may rarely present with ocular findings and should be considered in the differential diagnosis when a patient has peripheral keratitis.

Purpose: To determine the type and prevalence of epithelial abnormalities in the intermediate postoperative period after penetrating keratoplasty and to define the donor and recipient variables that influence the status of the graft epithelium., Design: Prospective cohort study., Methods: We prospectively followed the clinical course of 80 patients after penetrating keratoplasty. We monitored the status of the corneal epithelium for 3 months after surgery using slit-lamp biomicroscopy and fluorescein staining of the epithelium. Donor characteristics, recipient preoperative and postoperative variables, and postoperative medications were recorded. Epithelial abnormalities were analyzed against these variables by using univariate and combined statistical models to determine the impact of each variable on postoperative epithelial pathology. Main outcome measures included punctate keratopathy, macro-epithelial defects, hurricane keratopathy, rim defects, and filamentary keratopathy., Results: Sixty-three percent of all patient visits demonstrated punctate epithelial keratopathy (PEK). Hurricane keratopathy (51%) and filamentary keratopathy (14%) constituted the next most commonly observed abnormalities. Older recipient age and the use of topical antibiotics were associated with a higher prevalence of punctate epithelial keratopathy. The odds ratio (OR) for a 1-year increase in age is 1.0276 (95% CI, 1.1013-1.0442), and the OR for using topical antibiotics is 6.9028 (95% CI, 3.1506-15.1239). Use of topical ofloxacin and increased time after surgery were associated with lower prevalence of punctate keratopathy; ORs were 0.9806 (95% CI, 0.9736-0.9876) and 0.3662 (95% CI, 0.1688-0.7943), respectively. Decreased corneal sensation and the presence of anterior blepharitis preoperatively were associated with an increase in hurricane keratopathy; ORs were 8.8265 (CI, 2.3837-32.6835) and 3.2815 (CI, 1.7388-6.1931), respectively. Total storage time for the donor material was also associated with an increased prevalence of hurricane keratopathy (OR, 1.0316; CI, 1.0052-1.0220). Patients with rim defects and macro-epithelial defects were more likely to have antibiotic and topical lubrication prescribed. No specific variable was found to have a significant association with filamentary keratopathy, except possibly for death-to-preservation time, which had a P value of .0587., Conclusions: Surface keratopathy is one of the most common complications of keratoplasty. Our study demonstrates that older age, preoperative lid disease, and decreased preoperative corneal sensation appear to increase the probability of clinically significant epithelial surface abnormalities after keratoplasty. Recognition of these risk factors in advance of surgery will alert the surgeon to the need for appropriate management.

The periplasmic dipeptide-binding protein from Escherichia coli has been purified, freed of bound endogenous ligands, and crystallized. Crystals of the protein in complex with added dipeptides have been subjected to X-ray analysis. The crystals grow as hexagonal bipyramids or eye-shaped disks which have the symmetry of space group P6(1). The unit cell dimensions are a = b = 183 A, c = 212 A, and the diffraction pattern extends to 3.2 A resolution with a conventional X-ray source.

In order to utilize 19F nuclear magnetic resonance (NMR) to probe the solution structure of Escherichia coli tRNAVal labeled by incorporation of 5-fluorouracil, we have assigned its 19F spectrum. We describe here assignments made by examining the spectra of a series of tRNAVal mutants with nucleotide substitutions for individual 5-fluorouracil residues. The result of base replacements on the structure and function of the tRNA are also characterized. Mutants were prepared by oligonucleotide-directed mutagenesis of a cloned tRNAVal gene, and the tRNAs transcribed in vitro by bacteriophage T7 RNA polymerase. By identifying the missing peak in the 19F NMR spectrum of each tRNA variant we were able to assign resonances from fluorouracil residues in loop and stem regions of the tRNA. As a result of the assignment of FU33, FU34 and FU29, temperature-dependent spectral shifts could be attributed to changes in anticodon loop and stem conformation. Observation of a magnesium ion-dependent splitting of the resonance assigned to FU64 suggested that the T-arm of tRNAVal can exist in two conformations in slow exchange on the NMR time scale. Replacement of most 5-fluorouracil residues in loops and stems had little effect on the structure of tRNAVal; few shifts in the 19F NMR spectrum of the mutant tRNAs were noted. However, replacing the FU29.A41 base-pair in the anticodon stem with C29.G41 induced conformational changes in the anticodon loop as well as in the P-10 loop. Effects of nucleotide substitution on aminoacylation were determined by comparing the Vmax and Km values of tRNAVal mutants with those of the wild-type tRNA. Nucleotide substitution at the 3' end of the anticodon (position 36) reduced the aminoacylation efficiency (Vmax/Km) of tRNAVal by three orders of magnitude. Base replacement at the 5' end of the anticodon (position 34) had only a small negative effect on the aminoacylation efficiency. Substitution of the FU29.A41 base-pair increased the Km value 20-fold, while Vmax remained almost unchanged. The FU4.A69 base-pair in the acceptor stem, could readily be replaced with little effect on the aminoacylation efficiency of E. coli tRNAVal, indicating that this base-pair is not an identity element of the tRNA, as suggested by others.