CONCLUSIONS: A strong up-regulation of oxidative/respira-tory burst involving the NADPH oxidase system, activated via theangiotensin-II and DAG-PKC pathways, occurs in kidneys of hyperox-aluric rats,reversible by Apocynin treatment.

Source of Funding: NIH NIDDK grant R01 DK078602

2122THE ROLE OF LONG-TERM LOADING OF CHOLESTEROL INRENAL CRYSTAL FORMATION

Yasuhiro Fujii*, Atsushi Okada, Kazumi Taguchi, Shuzo Hamamoto,Masahito Hirose, Yasunori Itoh, Takahiro Yasui, Yoshiyuki Kojima,Keiichi Tozawa, Yutaro Hayashi, Kenjiro Kohri, Nagoya, Japan

INTRODUCTION AND OBJECTIVES: We studied the effects ofcholesterol load on crystal formation in rats receiving a standard diet ora high fat diet.

METHODS: Sixty male rats were randomized to two groupsand were fed either a standard diet (SD group) or a high fat diet (HFDgroup) for 8 weeks. Then the two groups were further divided into fourgroups. SD group, HFD group, SD � EG (ethylene glycol administra-tion) group, and HFD � EG group. Twenty-four-hour urine sampleswere collected in week 0, week 1, and week 2, and oxalate excretionand citrate excretion were measured. The excretion of phosphorus,magnesium, and creatinine for 24 hours was measured. Serum so-dium, potassium, chloride, calcium, phosphate, magnesium, creatinine,total cholesterol, triglyceride, HDL-cholesterol and glucose were deter-mined. The kidney tissues were obtained to perform hematoxyline-eosine staining and Pizzolato’s staining to detect oxalate-containingcrystals.

RESULTS: The average body weight in HFD groups andHFD � EG group in week 0 was significantly higher than that of SDgroup and SD � EG group. The calcium oxalate crystal deposition wasnot observed in all groups in week 0. HFD � EG group in week 1 hadsporadically calcium oxalate crystal deposition in renal distal tubularcells and tubular lumens. In week 2, the number of crystal deposition inHFD � EG group was increased remarkably. The crystals were slightlyobserved in SD � EG group in week 2. The excretion of urinary calciumand phosphate in HFD group and HFD � EG group was significantlyhigher than that of the SD group and SD � EG group in week 0. Theamount of urinary citrate excretion in the SD group and SD � EG groupshowed a significantly higher value compared with that of the HFDgroup and HFD � EG group in week 0. The level of serum totalcholesterol in the HFD group and HFD � EG group was highercompared to that in the SD group and SD � EG group. The serumtriglyceride level was not significantly different in the four groups inweek 0. Interestingly, the level of triglyceride of EG administrationgroups (SD � EG and HFD � EG group) was significantly higher thanthat in EG no-administration groups (SD group and HFD group) in week1 and week 2. The serum glucose level in the HFD group and HFD �EG group was significantly higher than that in the SD group and SD �EG group in week 0. In week 2, the glucose level of EG administrationgroups (HDF � EG group and SD � EG group) was significantly lowerthan that of EG no-administration groups (HFD group and SD group).

CONCLUSIONS: This result suggested that long-term loadingof cholesterol could increase renal crystal formation.

Source of Funding: None

2123HOLMIUM:YAG OPTICAL FIBER BURNBACK VARIES WITHSTONE COMPOSITION

Jennifer Castelbuono*, Columbus, OH; Joel Teichman, Vancouver,Canada; Bodo Knudsen, Columbus, OH

INTRODUCTION AND OBJECTIVES: Optical fiber tip degra-dation (fiber burnback) occurs at variable rates during laser lithotripsyof renal stones. Prior research showed more fiber damage with calcium

oxalate monohydrate (COM), calcium phosphate (CP), and struvitestones compared to uric acid stones. We hypothesize that the rate offiber burnback varies with stone composition.

METHODS: An ex-vivo testing apparatus was used to bring a240 �m core sized optical fiber into contact with stones of knowncomposition (UA, CP, COM, and artificial Bego). Lead tape was used toensure consistent pressure was applied to the stone. The holmium:YAG laser was activated until 100 J were delivered. Settings of 400 mJand 1500 mJ at 5Hz were tested for all stone compositions. Theamount of fiber burnback was measured. Fiber energy transmissionwas measured before and after each trial. Multiple trials with eachstone composition were performed.

RESULTS: Contact with COM and CP stones resulted ingreater burnback than with UA stones at both 400 mJ and 1500 mJ(p � 0.05). Contact with Bego stones resulted in similar burnback toCOM and CAP stones, but greater than UA stones (p � 0.05). ForCOM, CP, and Bego stone compositions, burnback increased at thehigher pulse energy setting (p � 0.05). Pulse energy did not alter therate of burnback with UA stones. Fiber energy transmission did notchange.

CONCLUSIONS: Optical fiber burnback varies with stone com-position and pulse energy setting with the exception of UA stones. Fiberburnback did not alter energy transmission. These findings are consis-tent with prior studies. A strategy of low pulse energy and high pulserepetition should minimize burnback while maintaining fragmentationefficiency.

COHORTBURNBACK MEAN

(�m) ENERGY TRANSMISSION (mJ)Bego (400 mJ) 0.148 535

Bego (1500 mJ) 0.787 481

Uric Acid (400 mJ) 0.026 515

Uric Acid (1500 mJ) 0.024 510

COM (400 mJ) 0.1 498

COM (1500 mJ) 0.671 500

CP (400 mJ) 0.175 511

CP (1500 mJ) 0.561 512

Source of Funding: None

2124IN VITRO COMPARISON OF PROTOTYPE MAGNETIC TOOLWITH CONVENTIONAL NITINOL BASKET FORURETEROSCOPIC RETRIEVAL OF STONE FRAGMENTSRENDERED PARAMAGNETIC WITH IRON-OXIDEMICROPARTICLES

Yung Tan*, dallas, TX; Steven Faddegon, Dallas, TX;Stacey McLeroy, Richardson, TX; Ephrem Olweny, Samuel Park,Dallas, TX; Raul Fernandez, Heather Beardsley, Arlington, TX;Margaret Pearle, Jeffrey Cadeddu, Dallas, TX

INTRODUCTION AND OBJECTIVES: We developed a proto-type magnetic tool for ureteroscopic extraction of magnetized stoneparticles and compared its efficiency of retrieval of magnetized calciumoxalate monohydrate (COM) stone particles with a conventional nitinolbasket using a bench-top ureteroscopic simulator.

METHODS: Iron oxide microparticles were successfully boundto human COM stones in sizes of 1-1.5mm, 1.5-2mm and 2-2.5mm.Several coated fragments of each size were implanted into the collect-ing system of a bench-top ureteroscopic simulator, and timed stoneextractions (5 minute trials) were performed for each fragment sizeusing either a back-loaded 8F magnetic tool mounted on a 0.038-inchguidewire or a conventional basket. Median number of fragmentsretrieved per timed trial was compared for the magnetic tool versus thebasket using the Mann-Whitney U test.

RESULTS: For 1-1.5mm fragments, the median number offragments retrieved within 5 min was significantly higher for the proto-type magnetic tool versus the nitinol basket (9.5 versus 3.5, p�0.03).For 1.5-2mm, the magnetic tool was more efficient but the difference in

Vol. 187, No. 4S, Supplement, Wednesday, May 23, 2012 THE JOURNAL OF UROLOGY� e857