The wound healing response after laser in situ keratomileusis and photorefractive keratectomy: elusive control of biological variability and effect on custom laser vision correction

Biological diversity in the wound healing response is thought to be a major factor limiting the predictability of the outcome of refractive surgical procedures such as laser in situ keratomileusis and photorefractive keratectomy. Corneal wound healing is critical to the success of topography-linked or wave front-linked excimer laser ablation to optimize visual performance. This is because of the importance of retaining subtle features of custom ablation and the tendency of epithelial hyperplasia and stromal remodeling to obscure these features following either procedure. The corneal wound healing response is exceedingly complex. Keratocyte apoptosis, which occurs in response to epithelial injury, is the earliest observable event in the wound healing cascades and is therefore an excellent target for pharmacological intervention. Alterations of surgical technique can be designed to limit keratocyte apoptosis and the subsequent events in corneal wound healing. Abnormalities of the cascades could contribute to the pathogenesis of corneal diseases. For example, recent data have suggested that perturbation of the keratocyte apoptosis/mitosis balance could underlie the development of keratoconus in a proportion of patients.

Complications of Laser in situ Keratomileusis: Etiology, Prevention, and Treatment

PURPOSE

To review the etiology, prevention, and management of laser in situ keratomileusis (LASIK) complications.

METHODS

Review of literature and the experience of the authors.

RESULTS

Careful preoperative screening is critical to prevention of many potential complications of LASIK. Flap complications that occur during surgery are typically managed by replacement of the flap and repeating the surgery or applying special methods such as transepithelial photorefractive keratectomy weeks to months following the initial procedure. A common source of serious complications is the use of a microkeratome that functions after improper assembly. Timely treatment of postoperative complications such as diffuse lamellar keratitis, flap striae, and infection is critical to an optimal outcome.

CONCLUSION

Most complications of LASIK can be treated effectively and have minimal effect on the final outcome after surgery, if appropriate methods are used for management.

Laser in situ keratomileusis versus photorefractive keratectomy in the correction of myopic astigmatism

PURPOSE

To evaluate retrospectively the effectiveness of astigmatism correction in eyes treated with laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

METHODS

Patients with low to moderate myopia with astigmatism ranging from +0.25 to +4.50 diopters were included in the study. PRK was performed on 62 eyes and LASIK on 70 eyes. Six-month data were analyzed with regard to astigmatism power, astigmatism axis, spherical equivalent, uncorrected visual acuity, vector astigmatism change, and topographic corneal regularity.

RESULTS

Mean astigmatism magnitude change was 0.54 +/- 0.76 in PRK-treated eyes and 0.60 +/- 0.67 in LASIK-treated eyes (61% versus 64% change, respectively, p = 0.61) at 6 months after surgery. Mean spherical correction change was -2.79 +/- 1.51 for PRK and -2.90 +/- 1.03 for LASIK (p = 0.63). Mean spherical equivalent change was -2.5 +/- 1.57 for PRK and -2.6 +/- 1.23 for LASIK (p = 0.73). Mean change in astigmatism axis was 20.8 +/- 73.1 for PRK and 33.8 +/- 81.7 for LASIK (p = 0.34). Mean change in uncorrected visual acuity (LogMar) was 0.84 +/- 0.26 for PRK and 0.89 +/- 0.23 for LASIK (p = 0.21). Mean vector-corrected astigmatism change was 0.88 +/- 0.66 for PRK and 0.95 +/- 0.59 for LASIK (p = 0.51). Mean vector-corrected astigmatism axis for PRK was 86.9 +/- 59 degrees and for LASIK 83.8 +/- -47.6 degrees (p = 0.75).

CONCLUSION

There was no significant difference in astigmatism correction between PRK and LASIK at 6 months after surgery.

Hyperopic laser in situ keratomileusis: primary and secondary treatments are safe and effective

PURPOSE

To retrospectively analyze the safety and efficacy of hyperopic laser in situ keratomileusis (LASIK) treatment of eyes with primary hyperopia and consecutive hyperopia after initial myopic treatment.

METHODS

Thirty-two eyes of 19 patients with primary hyperopia (group 1) and 37 eyes of 26 patients with consecutive hyperopia after initial myopic LASIK overcorrection (group 2) that had LASIK for hyperopia with the Hansatome microkeratome and VISX S2 Smoothscan excimer laser with 6 months' follow-up after surgery were analyzed. Uncorrected visual acuity, best spectacle-corrected visual acuity, fogged manifest refraction, and corneal topography with corneal irregularity measurement (CIM) were evaluated 1 month, 3 months, and 6 months after surgery.

RESULTS

In group 1, the mean preoperative cycloplegic spherical equivalent was +4.0 +/- 4.5 diopters (D) (range, +1.5 to + 8.75 D) and the 6-month postoperative cycloplegic spherical equivalent was +0.26 +/- 1.74 D (range, -3.00 to +2.75 D). Fifty-three percent of eyes (n= 17) in group 1 were within 1 D of emmetropia. Sixty-six percent of eyes (n= 21) had uncorrected visual acuity of at least 20/40. Three eyes (9%) lost two lines of best spectacle-corrected visual acuity. Changes in uncorrected visual acuity, best spectacle-corrected visual acuity, spherical equivalent, and the CIM topographic index 6 months after surgery were statistically significant compared with the preoperative values. In group 2, the mean preoperative cycloplegic spherical equivalent was +1.58 +/- 0.35 D (range, +0.125 to +2.75 D), and the mean postoperative cycloplegic spherical equivalent was -0.48 +/- 0.46 (range, -2.75 to +0.38 D). Eighty-six percent of eyes (n= 32) were within 1 D of emmetropia. Eighty-four percent of eyes (n= 31) in group 2 had uncorrected visual acuity of at least 20/40. One eye (2.7%) lost two lines of best spectacle-corrected visual acuity. Complications included an epithelial nest that resolved 3 months after surgery in one eye in group 2.

CONCLUSIONS

LASIK is a relatively safe treatment of primary hyperopia and hyperopia resulting from overcorrection after initial LASIK treatment of myopia (consecutive hyperopia). Patients with high hyperopia (>5 D) are at risk for loss of two lines of best spectacle-corrected visual acuity. A reduction in the level of attempted correction appears to be necessary in the treatment of consecutive hyperopia.

Recovery of uncorrected visual acuity after laser in situ keratomileusis or photorefractive keratectomy for low myopia

PURPOSE

To compare uncorrected visual acuity and refractive error in patients undergoing photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) between 1 week and 6 months after surgery.

METHODS

All eyes underwent PRK or LASIK with the VisX StarS2 excimer laser. We retrospectively analyzed data from 77 random eyes of 77 patients in the PRK group and 76 eyes of 76 patients in the LASIK group. All eyes had a low myopic refractive error (spherical equivalent range, -0.88 diopters (D) to -5.13 D; mean PRK. -2.8 +/- 0.20 D: LASIK, -2.5 +/- 0.22 D). Uncorrected visual acuity and manifest refractive error were evaluated 1 week, 1 month, and 6 months after surgery.

RESULTS

Each eye undergoing PRK was paired with an eye undergoing LASIK for a similar level of spherical equivalent. Mean uncorrected visual acuity after 1 week was 0.85 +/- 0.06 (20/25, logMAR 0.12 +/- 0.04) for the PRK group and 1.01 +/- 0.06 (20/20, logMAR 0.01 +/- 0.03) for the LASIK group (p < 0.001). Mean spherical equivalent after 1 week was 0.23 +/- 0.12 D for the PRK group and -0.02 +/- 0.07 D for the LASIK group (p = 0.02). Mean uncorrected visual acuity after 1 month was 1.03 +/- 0.05 (20/20, logMAR 0.02 +/- 0.03) for the PRK group and 1.05 +/- 0.05 (20/20. -0.02 +/- 0.03) for the LASIK group (p = 0.16). Mean spherical equivalent after I month was 0.19 +/- 0.10 D for the PRK group and -0.02 +/- 0.09 D for the LASIK group. This difference was statistically significant (p = 0.02), but was unlikely to be clinically significant. Mean uncorrected visual acuity after 6 months was 1.05 +/- 0.06 (20/20, logMAR -0.01 +/- 0.03) for the PRK group and 1.06 +/- 0.05 (20/20, logMAR -0.14 +/- 0.03) for the LASIK group (p = 0.41). Mean spherical equivalent after 6 months was 0.02 +/- 0.08 D for the PRK group and 0.00 +/- 0.08 D for the LASIK group (p = 0.35).

CONCLUSION

Uncorrected visual acuity 1 week after surgery is significantly better in eyes undergoing LASIK than in eyes undergoing PRK. Both procedures provide functional vision by 1 week after surgery. The difference does not relate to refractive error, which was similar between the two groups, but to differences in healing of the epithelium. By 1 month after surgery, there is no difference in mean uncorrected visual acuity between eyes that undergo PRK or LASIK for low myopia.

Three-year outcome of endovascular treatment of superficial femoral artery occlusion

HYPOTHESIS

Patency after primary percutaneous transluminal angioplasty (PTA) and stenting of superficial femoral artery (SFA) occlusions is better than historical experience with PTA alone.

DESIGN

Consecutive case series of primary PTA with stenting, and follow-up with duplex imaging every 6 months (mean +/- SD follow-up, 32 +/- 15 months).

SETTING

Veterans Affairs medical center.

PATIENTS AND METHODS

Patients were 57 previously untreated men with 71 limbs having chronic atherosclerotic SFA occlusion with suprageniculate reconstitution and patent tibial runoff. Critical ischemia (Society for Vascular Surgery [SVS] category, 4-6) was present in 7 (10%), the remainder had intermittent claudication only (SVS, 1-3).

INTERVENTIONS

Guidewire recanalization followed by PTA, Wallstent deployment, and adjunctive thrombolysis as necessary; 19 limbs (27%) required thrombolysis to manage periprocedural thrombosis.

MAIN OUTCOME MEASURES

Cumulative patency, limb salvage, and complications.

RESULTS

Length (mean +/- SD) of occlusion was 14.4 +/- 9.9 cm. Length of stented artery was 24.3 +/- 11.1 cm. Ankle brachial index increased from 0.59 +/- 0.14 to 0.86 +/- 0.16 (P<.001) after stenting. One- and 3-year patencies were as follows: primary, 54.6% +/- 6.3% and 29.9% +/- 6.6%; assisted primary, 72.3% +/- 5.6% and 59.0% +/- 6.8%; and secondary, 81.6% +/- 4.8% and 68.3% +/- 6.5%. Three-year secondary patency when periprocedural thrombolysis was required was 35.7% +/- 12.5% compared with 70.6% +/- 7.4% for limbs not requiring periprocedural thrombolysis (P=.02); the differences in occlusion length and severity of ischemia were not significant between these 2 groups. Limbs undergoing adjunctive PTA during angiography 6 to 12 months after initial stenting had 63.0% +/- 13.3% patency at 3 years compared with 100% patency in limbs not requiring PTA at 6 to 12 months angiography (P=.046). Periprocedural mortality and morbidity were 2.8% and 15.5%, respectively. Three of the 7 limbs with critical ischemia underwent amputation during follow-up compared with 2 (3%) of 64 limbs with functional ischemia (chi(2) test, P<.006). A mean of 1.8 endovascular interventions per limb were performed.

CONCLUSIONS

Percutaneous transluminal angioplasty and stenting yielded higher patency rates than historical controls undergoing PTA alone. When periprocedural thrombolysis is required, subsequent patency appears to be significantly worse. Poor results after PTA and stenting of limbs with critical ischemia and the need for additional endovascular therapy limit the technique's utility.

Threats to the surgical residency in the academic medical center

Threats to the current form of surgical training in the academic medical center include financial pressures from the government and managed care organizations. A diminishing medical student interest in surgical careers has been noted. The constraints of managed care hold the potential to introduce weaknesses in surgical training in the academic medical center.

Socioeconomic status and the prevalence of health problems among married couples in late midlife

OBJECTIVES

This study analyzed the association between socioeconomic status (SES) and the prevalence of mutually occurring health problems among married couples in late midlife.

METHODS

Data consisted of 4746 married couples aged 51 to 61 years from the 1992 US Health and Retirement Study. Two health measures were used: (1) self-assessed health status and (2) an index of functional limitations and activity restrictions. SES indicators were household income, education, and insurance coverage.

RESULTS

In general, after adjustment for age cohort, a strong association was found between the health of a married individual and the health of his or her spouse. SES was highly associated with the joint occurrence of health problems among marriage partners.

CONCLUSIONS

Public health policy should pay particular attention to the interaction between health, SES, and interpersonal relationships.

Results of a clinical trial of clinafloxacin versus imipenem/cilastatin for intraabdominal infections

OBJECTIVE

Clinafloxacin is a novel quinolone with wide activity against the plethora of microorganisms encountered in intraabdominal infections. This trial was performed to examine its clinical efficacy.

SUMMARY BACKGROUND DATA

Clinafloxacin is representative of a new class of quinolones with considerable antimicrobial activity resulting from their mechanisms of action and pharmacodynamics. There is, however, concern about specific potential toxicities, including photosensitivity.

METHODS

This prospective, randomized, double-blind trial was conducted to compare clinafloxacin with imipenem/cilastatin as adjuncts in the management of complicated intraabdominal infections.

RESULTS

Five hundred twenty-nine patients were included in the intent-to-treat population, with 312 meeting all criteria for the valid population. Patients with a wide range of infections were enrolled; perforated or abscessed appendicitis was the most common (approximately 50%). One hundred twenty-three of the 150 valid patients treated with clinafloxacin (82%) had successful outcomes, as did 130 of the 162 (80%) treated with imipenem. For the intent-to-treat groups, 219 of 259 patients treated with clinafloxacin (85%) had successful outcomes, as did 219 of 270 patients treated with imipenem/cilastatin (81%). Treatment failure occurred in 39 patients who underwent drainage. There were substantially more gram-negative organisms recovered from the patients with treatment failure who were initially treated with imipenem/cilastatin.

CONCLUSIONS

The results of this study clearly demonstrate the safety and efficacy of clinafloxacin in the treatment of a range of intraabdominal infections, and in patients with a broad range of physiologic disturbances.

Discoidin domain receptor (DDR) 1 and 2: collagen-activated tyrosine kinase receptors in the cornea

Discoidin domain receptor (DDR) 1 and 2 have recently been found to serve as receptors for several collagen types. These receptors have been found to modulate cell proliferation and metalloprotease expression in response to collagen stimulation. The purpose of this study was to examine expression of DDR1 and DDR2 in the cornea and to determine the effect of several collagen types on proliferation and response to pro-apoptotic cytokines by corneal fibroblasts. DDR1 and DDR2 mRNAs were detected by RT-PCR. Proteins were detected by immunocytochemistry and immunoprecipitation with Western blotting. Cell proliferation in response to acetic acid-solubilized collagen type I, II, IV, IX or X was determined by cell counting. The effect of these collagen types on Fas-stimulating antibody-induced cell death was determined by trypan blue assay. DDR1 and DDR2 mRNAs were detected in each major human cell type of the cornea. Both were also detected in ex vivo human corneal epithelium. DDR1 and DDR2 proteins were detected in all three major cell types in culture and in human corneal tissue. Collagen types I, II, IV, IX and X stimulated proliferation, but had no effect on Fas-mediated apoptosis, of corneal fibroblasts. DDR1 and DDR2 tyrosine kinase receptors are expressed in the cornea. Collagen-stimulated mitosis of corneal fibroblasts in culture is likely mediated by the DDR receptors. Collagen had no effect on Fas-mediated apoptosis of corneal fibroblasts.

Control of directionality in the site-specific recombination system of the Streptomyces phage phiC31

The genome of the Streptomyces temperate phage phiC31 integrates into the host chromosome via a recombinase belonging to a novel group of phage integrases related to the resolvase/invertase enzymes. Previously, it was demonstrated that, in an in vitro recombination assay, phiC31 integrase catalyses integration (attP/attB recombination) but not excision (attL/attR). The mechanism responsible for this recombination site selectivity was therefore investigated. Purified integrase was shown to bind with similar apparent binding affinities to between 46 bp and 54 bp of DNA at each of the attachment sites, attP, attB, attL and attR. Assays using recombination sites of 50 bp and 51 bp for attP and attB, respectively, showed that these fragments were functional in attP/attB recombination and maintained strict site selectivity, i.e. no recombination between non-permissive sites, such as attP/attP, attB/attL, etc., was observed. Using bandshifts and supershift assays in which permissive and non-permissive combinations of att sites were used in the presence of integrase, only the attP/attB combination could generate supershifts. Recombination products were isolated from the supershifted complexes. It was concluded that these supershifted complexes contained the recombination synapse and that site specificity, and therefore directionality, is determined at the level of stable synapse formation.

New epidemiology for postoperative nosocomial infections

Changes in health care delivery systems over the last decade have resulted in a major increase in outpatient surgery and a higher severity of illness for inpatients. We sought to determine the effects of this change on the epidemiology of postoperative surgical infections. Historical data on incidence and epidemiology of infection were obtained from peer-reviewed articles published between 1960 and 1999 (MEDLINE). All nosocomial infections in 5035 patients admitted to a tertiary-care university hospital surgical intensive care unit between January 1994 and December 1997 were prospectively identified and classified as wound, urinary tract, bloodstream, or pneumonia. Incidence of bacterial isolates at each site was also recorded. From these data we determined infection rates per 100 admissions. We also identified all device-related nosocomial infections and calculated infection rates. Comparisons between time periods were made. In the 1960s wound infections constituted the predominant postoperative infection at 46 per cent. This was replaced by urinary tract infection in the 1970s (44%) and 1980s (32%) and closely followed by bloodstream infections (25%). In the 1990s nosocomial pneumonia became the most common postoperative infection, comprising 43 per cent of surgical intensive care unit infections. Analysis of the bacteriology also revealed changing trends with primarily gram-positive organisms in the 1960s followed by an increase in methicillin-resistant Staphylococcus in the 1970 to 1980s, and currently resistant gram-negative bacteria predominate. The incidence of fungal infections has steadily increased. This survey identified a new epidemiology for postoperative surgical infections. Over the last several decades the reported wound infections have been markedly decreased and there is little change in urinary tract infection. Nosocomial pneumonia with resistant gram-negative bacteria now predominates along with increased incidence of fungal infections. Currently, postoperative infections are now more severe, involve critical organs, and require close monitoring of the changing patterns of pathogens.

Caspase inhibitor z-VAD-FMK inhibits keratocyte apoptosis, but promotes keratocyte necrosis, after corneal epithelial scrape

The purpose of this study was to determine whether the caspase inhibitor z-VAD-FMK could be applied topically prior to epithelial scrape injury to inhibit keratocyte apoptosis. Rabbit corneas were treated with z-VAD-FMK or vehicle alone prior to epithelial scrape injury. Cell fate was analysed at 4 hr after epithelial scrape using quantitative TUNEL assay, propidium iodide staining, and transmission electron microscopy. Less stained anterior stromal keratocytes were detected with the quantitative TUNEL assay in corneas pre-treated with z-VAD-FMK than in corneas pretreated with vehicle at 4 hr after epithelial scrape. This difference appeared to be confirmed by propidium iodide staining of keratocyte nuclei. It was observed that fewer nuclei were stained with propidium iodide in the DMSO vehicle treated corneas compared to the z-VAD-FMK treated corneas. Analysis of corneas with transmission electron microscopy, however, indicated that many anterior stromal keratocytes in corneas pretreated with z-VAD-FMK, but not vehicle, had cell morphologic changes more consistent with necrosis. Although pretreatment of corneas with the caspase inhibitor z-VAD-FMK inhibited keratocyte apoptosis detected with the TUNEL assay, transmission electron microscopy revealed that many anterior stromal keratocytes in z-VAD-FMK-treated corneas instead died by necrosis. Thus, z-VAD-FMK is unlikely to be useful to modulate corneal would healing through inhibition of keratocyte apoptosis induced by epithelial injury. The TUNEL assay should not be used to monitor cell fate without confirmation using analyses that also detect necrosis.

Angioplasty and stent placement in chronic occlusion of the superficial femoral artery: technique and results

PURPOSE

To improve the patency rate for angioplasty in chronic occlusion of the superficial femoral artery by deploying stents after angioplasty.

MATERIALS AND METHODS

Angioplasty and stent placement were performed in 61 arteries in 48 male patients. The mean occlusion length was 13.5 cm and the mean stent length was 30 cm. Patency rates were analyzed at 6 months and at 1, 2, 3, and 4 years. The predictors of restenosis were analyzed by univariate and multiple logistic regression.

RESULTS

Patency rates were 87% at 6 months, consisting of 74% primary, 6% primary assisted, and 7% secondary; 79% at 1 year, consisting of 47% primary, 19% primary assisted, and 13% secondary; 72% at 2 years, consisting of 36% primary, 26% primary assisted, and 10% secondary; 70% at 3 years, consisting of 26% primary, 22% primary assisted, and 22% secondary; and 63% at 4 years, consisting of 25% primary, 0% primary assisted, and 38% secondary. There was a 15% morbidity rate and one mortality as a result of retroperitoneal bleeding. Better patency rates were noted at all time intervals in diabetic limbs, 7-mm-diameter versus 10-mm-diameter stents, shorter obstructions and shorter stents, nonsmokers, in limbs in which urokinase was not necessary after stent deployment, and in limbs with an International Society of Cardiovascular Surgery (ISCVS) classification under 3. Patency rates were not affected by age, race, number of trifurcation vessels patent, experience in performing the procedures, and procedures requiring less time. By multivariate logistic analysis, the independent predictors of patency at 6 months were postprocedure ankle/brachial index (ABI) and shorter stent length; at 1 year, preprocedure ABI, shorter stent length, and the presence of diabetes; at 2 years, preprocedure ABI and the presence of diabetes; and at 3 years, the preprocedure ABI.

CONCLUSIONS

The techniques used to reestablish antegrade flow in these superficial femoral arteries yielded a high success rate. In addition, the use of angioplasty with stents may improve patency rates over angioplasty without stents.

Bowman's layer structure and function: critical or dispensable to corneal function? A hypothesis

PURPOSE

The purpose of this article is to review available information regarding development, structure, and function of Bowman's layer in the cornea. Disease-related abnormalities of Bowman's layer are described. A hypothesis is advanced to explain the development and maintenance of Bowman's layer.

METHODS

Literature review and hypothesis formulation based on previous studies.

RESULTS

Information is presented that supports the hypothesis that Bowman's layer forms as a result of cytokine-mediated interactions occurring between corneal epithelial cells and keratocytes that include chemotactic and apoptotic effects on the keratocytes. This hypothesis suggests that Bowman's layer results from such interactions beginning in early development and continuing into adulthood in humans and other animals, such as chickens.

CONCLUSIONS

Bowman's layer may be a visible indicator of ongoing stromal-epithelial interactions in the human and have no critical function in corneal physiology. Bowman's layer is commonly destroyed in diseases such as advanced bullous keratopathy where stromal-epithelial interactions may be interrupted. Bowman's-like layers often form in response to epithelium, for example when epithelial plugs extend into the stroma in corneas with radial keratotomy incisions.

Meeting the needs of rural breast cancer survivors: what still needs to be done?

As screening and treatment for breast cancer improve, learning about survivors' post-treatment needs becomes increasingly important. Focus groups (n = 23) were conducted with breast cancer survivors (n = 128) in rural Washington communities during a 5-month period in 1996 to explore ways to improve the lives of rural breast cancer survivors and to expand existing knowledge of breast cancer survivorship. Survivors reported positive and negative outcomes of their cancer experience. Results indicate that the needs of many women with breast cancer, particularly women diagnosed with late-stage disease, are not being met. Participants diagnosed with late-stage cancer were more likely than participants diagnosed with early-stage cancer to comment about being treated poorly by the medical system and to voice a need for increased support and educational services for breast cancer patients. Rural survivors, regardless of stage at diagnosis, reported needing more education about breast cancer and more emotional support after diagnosis. Further efforts to facilitate support and education within the context of medical care and to improve patient-clinician relationships are needed.

The aneurysm detection and management study screening program: validation cohort and final results. Aneurysm Detection and Management Veterans Affairs Cooperative Study Investigators

BACKGROUND

We previously reported the prevalence and associations of abdominal aortic aneurysm (AAA) in 73451 veterans aged 50 to 79 years who underwent ultrasound screening.

OBJECTIVE

To understand the prevalence of and principal positive and negative risk factors for AAA, and to assess reproducibility of our previous findings.

METHODS

In the new cohort of veterans undergoing screening, 52 745 subjects aged 50 to 79 without history of AAA underwent successful ultrasound screening for AAA, after completing a questionnaire on demographics and potential risk factors.

RESULTS

We detected AAA of 4.0 cm or larger in 613 participants (1.2%; compared with 1.4% in the earlier cohort). The direction and magnitude of the important associations reported in the first cohort were confirmed. Respective odds ratios for the major associations with AAA for the second and for the combined cohorts were as follows: 1.81 and 1.71 for age (per 7 years), 0.12 and 0. 18 for female sex, 0.59 and 0.53 for black race, 1.94 and 1.94 for family history of AAA, 4.45 and 5.07 for smoking, 0.50 and 0.52 for diabetes, and 1.60 and 1.66 for atherosclerotic diseases. The excess prevalence associated with smoking accounted for 75% of all AAAs of 4.0 cm or larger in the total population of 126 196. Associations for AAA of 3.0 to 3.9 cm were similar but tended to be somewhat weaker.

CONCLUSIONS

Our findings confirm our previous cohort findings. Age, smoking, family history of AAA, and atherosclerotic diseases remained the principal positive associations with AAA, and female sex, diabetes, and black race remained the principal negative associations.

Glycoprotein IIb/IIIa receptor inhibitor attenuates platelet aggregation induced by thromboxane A2 during in vitro nonpulsatile ventricular assist circulation

A recent development in antithrombotic research allows the inhibition of platelet aggregation via protection of the glycoprotein IIb/IIIa receptor on the platelet membrane. We hypothesized that a GP IIb/IIIa receptor inhibitor would inhibit thromboxane-induced platelet aggregation during circulation in our in vitro ventricular assist device (VAD) circuit and preserve long-term platelet function. Twenty-one in vitro nonpulsatile centrifugal VAD circuits were simulated for 4 days using 450 ml of fresh human whole blood with or without glycoprotein IIb/IIIa receptor inhibitor (tirofiban). Platelet aggregation and degranulation were measured in whole blood induced by ristocetin, collagen, ADP, and thromboxane A2 (TXA2). The tirofiban-treated group preserved the platelet count and tended to exert these beneficial effects by inhibiting pathologic platelet aggregation induced by TXA2, collagen, and ADP as well as degranulation. Tirofiban may be useful in preserving platelet number and function during clinical VAD use.

Modulation of TNF-alpha-induced apoptosis in corneal fibroblasts by transcription factor NF-kappaB

PURPOSE

Previous studies have suggested no role for tumor necrosis factor (TNF)-alpha in the modulation of apoptosis in corneal fibroblasts. However, recent investigations have demonstrated that nuclear factor (NF)-kappaB activation by TNF-alpha mediates negative apoptotic effects that must be blocked to unmask the apoptotic effects of TNF-alpha in vitro. The purpose of this study was to investigate the role of transcription factor NF-kappaB in the suppression of TNF-alpha-induced apoptosis of corneal fibroblasts.

METHODS

mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR) and RNase protection assay. Proteins were detected by immunocytochemistry and immunoprecipitation with Western blot analysis. Cell death was evaluated by trypan blue exclusion assay in corneal fibroblasts treated with TNF-alpha in presence or absence of the specific inhibitor of NF-kappaB activation, SN50, actinomycin D, or actinomycin D with dexamethasone, ketorolac tromethamine, or diclofenac sodium. Apoptosis was monitored by trypan blue exclusion, colorimetric cell assay, CPP32 activation assay, DNA fragmentation assay, and transmission electron microscopy. NF-KB activation was monitored using electrophoretic gel shift assay.

RESULTS

TNF-alpha, TNF receptor (R)I, and TNFRII mRNAs were detected in all three cultured corneal cell types and in ex vivo corneal epithelium using RT-PCR. TNF-alpha mRNA was also detected in ex vivo corneal epithelium, corneal epithelial cells, and stromal fibroblasts with the RNase protection assay. TNF-alpha, TNFRI, and TNFRII proteins were detected by immunocytochemistry in all three major corneal cell types in human corneal tissue. TNF-alpha protein was also detected in ex vivo corneal epithelium, primary corneal epithelial cells, and primary stromal fibroblasts using immunoprecipitation and Western blot analysis. TNF-alpha stimulated corneal fibroblast cell death when NF-kappaB activation was blocked with actinomycin D or SN50. Enhanced cell death was noted with dexamethasone, ketorolac tromethamine, or diclofenac sodium when used in the presence, but not in the absence, of actinomycin D. A gel shift assay revealed induction of NF-KB by TNF-alpha and suppression of induction in the presence of actinomycin D or SN50, but not by the control peptide SN50M.

CONCLUSIONS

The TNF-alpha receptor system is expressed in the cornea, and NF-kappaB activation is an important regulator of TNF-alpha-mediated corneal fibroblast apoptosis. Nonsteroidal anti-inflammatory agents or corticosteroids may potentiate corneal fibroblast apoptosis in response to cytokine stimulation.

Role of apoptosis in wound healing in the cornea

Anterior keratocytes undergo apoptosis in response to epithelial injury. This likely represents mechanical activation of systems that vigilantly monitor the corneal epithelium for injury produced by pathogenic viruses. Keratocyte apoptosis is the first change noted after procedures in which the epithelium is injured and may be an initiator of the subsequent wound healing cascade. The working hypothesis is that inhibition of keratocyte apoptosis will limit the subsequent wound healing response. The keratocyte apoptosis response varies with the specific type of epithelial injury induced by a particular refractive surgical procedure, such as photorefractive keratectomy or laser in situ keratomileusis. Continuing efforts aim to identify pharmacological agents that effectively inhibit keratocyte apoptosis without promoting keratocyte necrosis.

Yield of repeated screening for abdominal aortic aneurysm after a 4-year interval. Aneurysm Detection and Management Veterans Affairs Cooperative Study Investigators

BACKGROUND

Little is known about the rate at which new abdominal aortic aneurysms (AAAs) develop or whether screening older men for AAA, if undertaken, should be limited to once in a lifetime or repeated at intervals.

METHODS

A large population of veterans, aged 50 through 79 years, completed a questionnaire and underwent ultrasound screening for AAA. Of these, 5151 without AAA on the initial ultrasound (defined as infrarenal aortic diameter of 3.0 cm or larger) were selected randomly to be invited for a second ultrasound screening after an interval of 4 years. Local records and national databases were searched to identify deaths and AAA diagnoses made during the study interval in subjects who did not attend the rescreening.

RESULTS

Of the 5151 subjects selected for a second screening, 598 (11.6%) had died (none due to AAA), and 20 (0.4%) had an interim diagnosis of AAA. A second screening was performed on 2622 (50.9%), of whom 58 (2.2%; 95% confidence interval, 1.6%-2.8%) had new AAA. Three new AAAs were 4.0 to 4.9 cm, 10 were 3.5 to 3.9 cm, and 45 were 3.0 to 3.4 cm. Independent predictors of new AAA at the second screening included current smoker (odds ratio, 3.09; 95% confidence, 1.74-5.50), coronary artery disease (odds ratio, 1.81; 95% confidence interval, 1.07-3.07), and, in a separate model using a composite variable, any atherosclerosis (odds ratio, 1.97; 95% confidence interval, 1.16-3.35). Adding the interim and rescreening diagnosis rates suggests a 4-year incidence rate of 2.6%. Rescreening only in subjects with infrarenal aortic diameter of 2.5 cm or greater on the initial ultrasound would have missed more than two thirds of the new AAAs.

CONCLUSIONS

A second screening is of little practical value after 4 years, mainly because the AAAs detected are small. However, the incidence that we observed suggests that a second screening after longer intervals (ie, more than 8 years) may provide yields similar to those seen in initial screening and therefore warrants further study.

Defective keratocyte apoptosis in response to epithelial injury in stat 1 null mice

Defects in apoptosis have been noted in signal transducer and activator of transcription (Stat) 1-null cells in vitro. The purpose of this study was to analyse the keratocyte apoptosis response that occurs in vivo in response to corneal epithelial injury in Stat 1null compared with control mice and to determine whether Stat 1null corneal fibroblasts have a defective response to death receptor activation in vitro. Corneal epithelial scrape injuries were performed in Stat 1-null and wild-type mice. Keratocyte apoptosis was monitored with the quantitative TUNEL assay and confirmed using transmission electron microscopy. Corneal fibroblast apoptosis in response to tumor necrosis factor (TNF) alpha, with and without inhibitors of nuclear factor kappa B (NF-kappaB) activation, was monitored using DNA laddering and the methylene blue assay. Significantly less keratocyte apoptosis was noted in Stat 1-null mice compared with wild-type controls. TNF alpha-induced apoptosis only occurred in wild-type mice in the presence of inhibitors of NF-kappaB activation. Corneal fibroblast TNF alpha-induced apoptosis was defective in Stat 1null corneal fibroblasts whether NF-kappaB activation was blocked or not. Stat 1 has an important role in the keratocyte apoptosis that occurs in response to corneal epithelial injury. Previous studies suggest that the defect is due to a lack of constitutive expression of caspases. This study demonstrates that this defect in apoptosis in Stat 1-null mice is present in vivo in Stat 1-null mice and suggests that Stat 1 could be a therapeutic target for transient inhibition of keratocyte apoptosis to modulate corneal wound healing.

Impaired elastogenesis in Hurler disease: dermatan sulfate accumulation linked to deficiency in elastin-binding protein and elastic fiber assembly

Hurler disease resulting from a deficiency in alpha-L-iduronidase, which causes an accumulation of dermatan sulfate and heparan sulfate glycosaminoglycans, is characterized by connective tissue and skeletal deformations, cardiomyopathy, cardiac valve defects, and progressive coronary artery stenosis. In this report, we present evidence that accumulation of dermatan sulfate but not heparan sulfate moieties is linked to impaired elastic fiber assembly that, in turn, contributes substantially to the development of the clinical phenotype in Hurler disease. Our data suggest that dermatan sulfate-bearing moieties bind to and cause functional inactivation of the 67-kd elastin-binding protein, a molecular chaperone for tropoelastin, which normally facilitates its secretion and assembly into elastic fibers. We demonstrate that, in contrast to normal skin fibroblasts and cells from Sanfilippo disease, which accumulate heparan sulfate, Hurler fibroblasts show reduced expression of elastin-binding protein and do not assemble elastic fibers, despite an adequate synthesis of tropoelastin and sufficient production of a microfibrillar scaffold of elastic fibers. Because cultured Hurler fibroblasts proliferate more quickly than their normal counterparts and the addition of exogenous insoluble elastin reduces their proliferation, we suggest that cell contacts with insoluble elastin play an important role in controlling their proliferation.

Incidence and prevention of epithelial growth within the interface after laser in situ keratomileusis

PURPOSE

To analyze the incidence of epithelial growth within the interface after laser in situ keratomileusis (LASIK) and describe a technique that may prevent its occurrence.

METHODS

Results were reviewed for all LASIK procedures performed by two surgeons using identical surgical technique with either the Automated Corneal Shaper or Hansatome microkeratome. After laser ablation, the bed and posterior surface of the flap were irrigated with 0.2 microM filtered basic salt solution, and the surfaces were swept with lint-free sponges to clear the interface of epithelial and other debris. An aspirating lid speculum connected to suction was used to evacuate irrigation fluid and debris from the field. After the flap was smoothed into position, a bandage contact lens was used for the first day after surgery to prevent lifting of the flap edge during blinking.

RESULTS

Seven hundred eighty-three eyes of 419 patients had primary LASIK, and 108 eyes had LASIK reoperation. Three eyes developed epithelial growth within the interface, with a minimum of 3 months of follow-up. The interface opacity appeared within 1 month of surgery in all three eyes. Two epithelial nests were small (1.0 and 1.5 mm in diameter, respectively) and did not increase in size on subsequent visits. Neither peripheral epithelial nest affected best-corrected visual acuity or caused any other sequelae. One ingrowth occurred early postoperatively in a case with a donut-shaped flap and was eliminated by transepithelial photorefractive keratectomy (PRK).

CONCLUSION

Irrigating, wiping the stromal interface with sponges. aspirating irrigation fluid and debris with a suctioning lid speculum, and use of a bandage contact lens for the first day after surgery during LASIK and LASIK enhancement may markedly reduce the incidence of epithelial growth within the interface.