Recanalize ureteral stents with focused ultrasound.

BACKGROUND: Maintaining ureteral patency is imperative to preventing renal injury and systemic infection. Ureteral stents are small conduits connecting the kidney and the bladder. They have been widely used to treat ureteral obstructions and ureteral leaks. The most problematic and frequent stent-associated complication is stent encrustation. This occurs when mineral crystals (e.g. calcium, oxalate, phosphorus, struvite) are deposited onto the surface and internal lumen of the stent. Encrustation can lead to the obstruction of a stent and increases risk of systemic infection. As a result, ureteral stents need to be replaced typically every 2-3 months. PURPOSE: In this study, we present a non-invasive, high-intensity focused ultrasound (HIFU)-based technique to recanalize obstructed stents. By taking advantage of the mechanical force produced by a HIFU beam, including acoustic radiation force, acoustic streaming, and cavitation, HIFU can break up encrustations, clearing the stent of obstruction. METHODS: The ureteral stents for this study were obtained from patients undergoing ureteral stent removal. Under the guidance of ultrasound imaging, the encrustation in the stents were located, and then targeted by HIFU at frequencies of 0.25 and 1 MHz. The duty cycle of HIFU was 10%, and the HIFU burst repetition rate was 1 Hz, while the HIFU amplitude was varied to find the threshold pressure that would displace encrustations. The treatment duration was limited at 2 min (or 120 shots from HIFU). The treatments were carried out in two different orientations (parallel and perpendicular) of the ureteral stent with respect to the HIFU beam. For each setting, five treatments were conducted for a maximum duration of 2 min. During the entire treatment, an ultrasound imaging system was used to monitor the movement of encrustations inside the stent. The peak negative HIFU pressures needed to move the encrustations inside the stent was recorded for quantitative analysis. RESULTS: Our results demonstrated that at both 0.25 and 1 MHz ultrasound frequencies, obstructed stents could be recanalized. At 0.25 MHz, the needed average peak negative pressure was 0.52 MPa in parallel orientation and 0.42 MPa in perpendicular orientation. At 1 MHz, the needed average peak negative pressure was 1.10 MPa in parallel orientation and 1.15 MPa in perpendicular orientation CONCLUSIONS: This first in-vitro study has demonstrated the feasibility of non-invasive HIFU to recanalize ureteral stents. This technology has a potential to reduce the need for ureteral stent exchange.

Global Health Outreach by United States Ophthalmology Residency Programs: Understanding of Host Country Systems-Based Practice.

INTRODUCTION: For medical residents, global health outreach is the first experience of learning how to develop partnerships with foreign medical systems. The overall objective of this project was to develop an overview of global health programs in U.S. ophthalmology residencies. The investigation focused on characterizing the goals and services offered, the didactics taught to residents, and the program director's understanding of systems-based practice gained in the host country. MATERIALS AND METHODS: An online survey was sent to all U.S. ophthalmology residency program directors. The two outcome measures of the study were characterization of global health outreach and didactics completed by U.S. ophthalmology residency programs and review of program director understanding of host country systems of care. RESULTS: Twelve program directors of 117 (10.26%) answered the survey. 100% of programs from the Department of Defense responded. Countries served included Ecuador, Panama, Honduras, Dominican Republic, India, Tanzania, Nepal, Bhutan, Guatemala, Micronesia, Haiti, Mongolia, Bolivia. Sixty five percent worked at a free-standing public hospital. Many programs offered resident participation with only 41.87% giving residents ACGME credit. Most programs (91.67%) offered fewer than 5 hours of global health didactics. When program directors were asked about their knowledge of host country systems of care, most noted understanding of the hospital functions like the referral system, transitions of care, hospital funding, and medical supply chain, but not of the perception of patients with chronic or congenital ophthalmic diseases, host country general or ophthalmic medical education, patient research safeguards and host country malpractice system. CONCLUSION: From the small sample of program directors, Ophthalmology residency program global health outreach varies in faculty and resident participation, and in goals and services offered. In addition, there was a wide variation in ophthalmology program director understanding of host country systems of care.

Microeconomic Benefit of Corneal Transplantation in a Developing Country via Public-Private Partnership Model.

BACKGROUND: We measured the microeconomic benefit, QOL, DALYs averted and clinical outcomes of corneal transplant surgery via a public-private partnership in Guyana. Corneas were obtained, ex gratia, from US eye banks, and the work was done at no cost to the patient or the Governments of USA or Guyana. METHODS: We obtained qualitative data using a "semi-structured interview technique" to question 60 recent recipients of corneal transplants in Guyana. Our questions covered schooling in children, training for job, and type and income of job, both before and after surgery. We also discussed improvement in family income and quality of life (QOL) using a Likert scale of 1 lowest to 5 highest. RESULTS: Our data came from five humanitarian missions from July 2014 to July 2017. All school-going children (n = 6) were able to return to school and participate in educational activities. Young adults (n = 13), were able to acquire new jobs (50%) or training positions (50%) with higher income. Patients in the middle-age adult group (n = 20) re-acquired their employment positions (25%) or found new work (75%). Elderly patients (n = 21) after transplant were able to perform odd jobs to increase the family income. A consistent theme across all age groups was a dramatic improvement in the QOL. Two hundred and sixty DALYs (4.3 per patient) were averted. In this cohort of 62 surgery cases, mean preoperative visual acuity was 0.03 and postoperative mean visual acuity was 0.20. CONCLUSIONS: We have shown microeconomic benefits and improved QOL of corneal transplantation in a low-income country.

Hepatolithiasis after Hepaticojejunostomy: Ascaris lumbricoides in the biliary tract.

BACKGROUND: Biliary ascariasis is a common problem in Third World countries and other underdeveloped areas of the world. Ascaris lumbricoides migrates into the biliary tree, where it is apparent commonly on diagnostic imaging. We present a unique case of a patient with chronic right upper quadrant abdominal pain, massive hepatolithiasis, and stricture of a previous hepaticojejunostomy in whom ascariasis was found. METHODS: A 28-year-old female presented to the emergency department with right upper quadrant abdominal pain, syncope, and seizure-like activity. She was found by magnetic resonance cholangiopancreatography to have cholangitis, choledocholithiasis, and bile duct stricture. After multiple radiographic studies, she was taken to the operating room for revision of a hepaticojejunostomy performed 10 years previously. RESULTS: Ascaris lumbricoides was found in the right intrahepatic bile duct, that had not been identified by multiple radiologic modalities. The worm was sent to the pathology department for identification. A Fogarty catheter was passed into the hepatic ducts for successful stone extraction. The hepaticojejunostomy was revised, with catheter placement in the Roux limb to accommodate radiologic stone extraction as necessary. Post-operatively, she was given a single dose of albendazole and discharged on hospital day 19. CONCLUSION: The worm was likely the nidus for the stricture and stone formation. Surgical exploration of the biliary tree was required to diagnose and treat her condition accurately. This case is unique in that typical means of diagnosis failed to identify the causative agent of hepatolithiasis because of the prior Roux-en-Y hepaticojejunostomy.

Long-term follow-up of free-floating epithelial inclusion cyst after radial keratotomy.

PURPOSE: To report the benign seven year follow-up on a free-floating anterior chamber epithelial inclusion cyst that did not require treatment. DESIGN: Retrospective observational case report. METHODS: Seven years of clinical observation of a patient who had radial keratotomy in 1998. RESULTS: The free-floating cyst showed no growth or untoward effects on the eye and required no treatment during the observation period. CONCLUSIONS: The long clinical course of our patient shows that epithelial inclusion cysts may be managed without treatment for many years with careful and frequent follow-up.

U.S. Air Force Mobile Ophthalmic Surgery Team.

OBJECTIVE: The objective of this study was to report the evolution of the U.S. Air Force Mobile Ophthalmic Surgical Team (MOST). METHODS: U.S. Air Force ophthalmologists at Wilford Hall Medical Center in San Antonio, Texas, designed a small, portable, rapid-response eye surgical team. Field testing with humanitarian deployments refined the deployment package and provided operational training. RESULTS: MOST successfully deployed to Central and South America, the Caribbean, and Africa 42 times since 1991, with 50,287 patients examined/treated and 4,812 surgeries performed. Realistic readiness training was provided for 80% of U.S. Air Force ophthalmologists and Army, Navy, and Reserve colleagues. Subsequent modifications to the MOST improved its capability while reducing the size and weight of the team, equipment, and supplies by 50%. CONCLUSIONS: Using MOST humanitarian missions as a refining model, U.S. Air Force deployable ophthalmic assets are modular, lightweight, and multifunctional, which allows commanders to custom-build an appropriate response to each unique contingency, disaster, or humanitarian need with mission-ready ophthalmologists.

Laser in situ keratomileusis flap stability during simulated aircraft ejection in a rabbit model.

PURPOSE: To determine the stability of the laser in situ keratomileusis (LASIK) flap in a rabbit model when subjected to vertical acceleration at nine times the force of gravity (+9 Gz) in an aircraft cockpit ejection simulator. METHODS: Thirty-six eyes from 25 New Zealand white rabbits underwent LASIK flap creation without laser photoablation. One month after surgery, the rabbits were sedated and harnessed in a cockpit ejection seat simulator used to train United States Air Force pilots. They then underwent a controlled rapid-sequence ejection at +9 Gz. Subsequently, the rabbits were euthanized and the corneas harvested for microscopic examination. Refractive measurements and corneal examination were made before LASIK flap creation and prior to and after the +9 Gz ejections. Determination of LASIK flap dislocation was based on clinical observation of flap slippage or a significant shift in pre-ejection to postejection cylinder axis. RESULTS: The average preoperative refraction of the rabbit eye was +1.83 D + 3.25 D x 086 degrees. The average change from pre-ejection to postejection was 0.04 D sphere, 0.02 D cylinder, 6.8 axis degrees, and 0.04 D spherical equivalent. The pre-ejection to postejection measurements were not statistically significantly different by a paired test. Laser in situ keratomileusis flap dislocation or ejection-induced corneal folds or striae were not clinically observed. Histologic examination revealed well-healed LASIK flaps but no reactive keratocytes at the central stromal-stromal interface. CONCLUSIONS: Healed LASIK flaps as created in this rabbit model without laser ablation are stable when subjected to a rapid vertical ejection at nine times the force of gravity.

Comparative biotransformation of radiolabeled [(14)C]omapatrilat and stable-labeled [(13)C(2)]omapatrilat after oral administration to rats, dogs, and humans.

Omapatrilat, a novel vasopeptidase inhibitor, is under development for the treatment of hypertension and congestive heart failure. This study describes the comparative biotransformation of radiolabeled [(14)C]- and stable-labeled [(13)C(2)]omapatrilat after administration of single oral doses to rats, dogs, and humans. The metabolites were identified by a combination of methods including reduction, hydrolysis, and comparison of high performance liquid chromatography retention times with those of the synthetic standards. Urinary metabolites were further characterized by liquid chromatography tandem mass spectrometry analysis. Prominent metabolites identified in human plasma, which were also present in rat and dog plasma, were S-methyl omapatrilat and S-2-thiomethyl-3-phenylpropionic acid. Omapatrilat accounted for only a small portion of the extractable radioactivity in plasma in all three species. A portion of the plasma radioactivity was unextractable in all three species (27-53%). The majority of unextractable radioactivity in plasma was characterized after dithiothreitol reduction to be omapatrilat and (S)-2-thio-3-phenylpropionic acid, both apparently bound to plasma proteins by reversible disulfide bonds. The major human urinary metabolites were the amine hydrolysis product, diasteromeric sulfoxide of (S)-2-thiomethyl-3-phenylpropionic acid, acyl glucuronide of S-methyl omapatrilat, and S-methyl omapatrilat. The minor metabolites were acyl glucuronide of (S)-2-thiomethyl-3-phenylpropionic acid, L-cysteine mixed disulfide of omapatrilat, diastereomers of S-methyl sulfoxide of omapatrilat, and S-methyl omapatrilat ring sulfoxide. The metabolic profiles of dog and human urine were qualitatively similar whereas rat urine showed only metabolites arising from hydrolysis of omapatrilat. Unchanged omapatrilat was not found in rat, dog, or human urine samples indicating extensive metabolism in vivo.