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Dive into the research topics where Gerald R. May is active.

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Featured researches published by Gerald R. May.


The Journal of Urology | 1985

Percutaneous Removal of Kidney Stones: Review of 1,000 Cases

Joseph W. Segura; Davide E. Patterson; Andrew J. LeRoy; Hugh J. Williams; David M. Barrett; Ralph C. Benson; Gerald R. May; Claire E. Bender

We report the results of 1,000 consecutive patients who underwent percutaneous removal of renal and ureteral stones. Removal was successful for 98.3 per cent of the targeted renal stones and 88.2 per cent of the ureteral stones. Complications, evolution and technique are discussed. Percutaneous techniques are an effective way to handle the majority of renal calculi and these techniques will continue to be important as shock wave lithotripsy becomes more widespread in the United States.


The New England Journal of Medicine | 1989

Dissolution of Cholesterol Gallbladder Stones by Methyl Tert-Butyl Ether Administered by Percutaneous Transhepatic Catheter

Johnson L. Thistle; Gerald R. May; Claire E. Bender; Hugh J. Williams; Andrew J. LeRoy; Nelson Pe; Craig J. Peine; Petersen Bt; McCullough Je

We treated 75 patients with symptomatic cholesterol gallstones by dissolving the stones with methyl tert-butyl ether (MTBE) instilled into the gallbladder through a percutaneous transhepatic catheter. The MTBE was continuously infused and aspirated manually four to six times a minute, for an average of five hours per day for one to three days; the treatment was monitored by fluoroscopy. The placement of the catheter and the administration of MTBE caused few side effects or complications, and treatment did not have to be stopped in any patient for this reason. In 72 patients there was complete dissolution of stones or more than 95 percent dissolution. Among 21 patients who were completely free of stones after treatment, 4 had recurrence of stone formation 6 to 16 months later. The other 51 patients had residual debris, which spontaneously cleared completely in 15 patients within 6 to 35 months; only 7 with persisting debris have had symptoms. Five of the initial 6 patients treated, but only 1 of the next 69 patients, have required surgery during follow-up periods of 6 to 42 months. We conclude that the dissolution of gallstones by MTBE delivered through a percutaneous transhepatic catheter is a useful alternative to surgery in selected patients with symptomatic cholesterol stones. Further study will be necessary to establish the long-term effectiveness of this treatment and its appropriate role in the management of the various types of gallstones.


Gastroenterology | 1985

Cholelitholysis using methyl tertiary butyl ether.

Mark Allen; Thomas J. Borody; Thomas F. Bugliosi; Gerald R. May; Nicholas F. LaRusso; Johnson L. Thistle

We tested methyl tertiary butyl ether both in vitro and in vivo to evaluate its efficacy as a potential cholesterol gallstone solvent for direct instillation into the human gallbladder or bile duct. Like diethyl ether, methyl tertiary butyl ether is an aliphatic ether with an excellent cholesterol-solubilizing capacity. However, unlike diethyl ether which vaporizes at body temperature, methyl tertiary butyl ether remains a liquid having a boiling point of 55.2 degrees C. In vitro, methyl tertiary butyl ether dissolved human gallstones (40%-94% cholesterol) within 60-100 min. In contrast, monooctanoin, an established gallstone solvent, required greater than 50 h to dissolve similar stones. By direct catheter instillation in 6 dogs, methyl tertiary butyl ether required only 4-16 h to dissolve gallstones surgically implanted in the gallbladder. The dogs tolerated methyl tertiary butyl ether with only minor clinical, biochemical, or histologic effects. We conclude that further evaluation of methyl tertiary butyl ether for dissolution of human gallbladder and biliary duct cholesterol stones is warranted.


The Journal of Urology | 1985

The Etiology and Treatment of Delayed Bleeding Following Percutaneous Lithotripsy

David E. Patterson; Joseph W. Segura; Andrew J. LeRoy; Ralph C. Benson; Gerald R. May

In 1,032 percutaneous stone manipulations the incidence of significant, documented or presumed vascular injuries was 0.9 per cent. Seven cases of pseudoaneurysm, arteriovenous fistula or vascular lacerations were found, all of which were diagnosed angiographically. The patients were treated successfully with transcatheter embolization techniques. Two additional patients experienced delayed bleeding, presumably from vascular injuries, which resolved spontaneously with conservative therapy. Arteriography should be performed in these patients with serious postoperative bleeding. Embolization of the peripheral vessel is preferable to flank exploration.


International Journal of Radiation Oncology Biology Physics | 1984

Analysis of failure following curative irradiation of gallbladder and extrahepatic bile duct carcinoma

Steven J. Buskirk; Leonard L. Gunderson; Martin A. Adson; Alvaro Martinez; Gerald R. May; Donald C. McIlrath; David M. Nagorney; Gregory K. Edmundson; Claire E. Bender; J. Kirk Martin

Twenty patients with carcinoma of the gallbladder (GB-4 patients) or extrahepatic bile ducts (EHBD-16 patients) received radiation therapy with curative intent between January, 1980 and December, 1982. All 20 received 4500-5000 rad in 180-200 rad fractions to the tumor and regional lymph nodes. A 1000 to 1500 rad external beam boost was delivered in 180-200 rad fractions in 10 patients who received external beam alone or concomitant 5-Fluorouracil (5-FU). Three of the four GB and 5 of the 16 EHBD patients received a transcatheter boost with 192-Iridium (192Ir) to a dose of 2000-2500 rad calculated at a 0.5-0.1 cm radius. An additional 2 patients with EHBD lesions received an intraoperative electron (IORT) boost of 1500-2000 rad in one fraction calculated to the 90% isodose. Survival and patterns of failure were analyzed by site and treatment method. All four patients with GB carcinoma are dead of disease at 5 1/2, 6, 9 and 10 months from the date of diagnosis respectively. Three of the four developed diffuse peritoneal carcinomatosis. Five of the 16 patients with EHBD carcinoma are alive with a median follow-up of 18 months (range 6-23 months). Four of the 5 patients received a transcatheter 192Ir or IORT boost and all are without evidence of disease. Four of 9 patients who had a subtotal resection with transection of tumor, dilatation of the bile ducts with probes or curettement of the bile ducts developed either diffuse peritoneal carcinomatosis (3 patients) or a recurrence in the surgical scar (2 patients). Local failure was documented in 3 of the nine patients treated with external beam alone +/- 5-FU, and has been documented in one of the seven patients who received an IORT or transcatheter 192Ir boost. Further experience is necessary to determine whether this aggressive treatment will result in long-term disease-free survival in these patients.


Mayo Clinic proceedings | 1985

Magnetic resonance imaging in a routine clinical setting.

Hillier L. Baker; Tom H. Berquist; Kispert Db; David F. Reese; O. Wayne Houser; Franklin Earnest; Glenn S. Forbes; Gerald R. May

The results of magnetic resonance imaging (MRI) examinations in the first 1,000 consecutive patients who were studied by this technique at our institution were reviewed to determine the disease states encountered, the sensitivity and accuracy of results, and the value of the examination as compared with computed tomography and other imaging procedures. The MRI device was a 0.15-tesla resistive magnet that used a variety of saturation recovery, spin echo, and inversion recovery pulse sequences to produce images. MRI was found equal to or superior to other imaging techniques in most cases. Exceptions included organs or body regions that are prone to excessive respiratory or vascular motion, lesions that necessitate exquisite spatial resolution for diagnosis, and lesions in which angulation of the viewing plane is necessary for optimal depiction. Fresh blood and calcification within a lesion were also difficult to detect with use of MRI.


Magnetic Resonance Imaging | 1985

Magnetic resonance imaging: application in musculoskeletal infection

Thomas H. Berquist; Manuel L. Brown; Robert H. Fitzgerald; Gerald R. May

Forty-two patients with clinically suspected osteomyelitis were examined using magnetic resonance imaging (MRI). Twenty-seven patients (64%) had previous surgery or fracture, and 15 (36%) were referred for differentiation of acute osteomyelitis from bone tumors or other pathologic conditions. MRI was compared with computed tomography in 12 cases and with 111In-labeled leukocytes scans in 22. With MRI, 92% of proved infections were detected, and bone and soft-tissue changes were more evident than with routine radiographs, tomography, or computed tomography. In patients with negative cultures and no previous surgery or fracture, it was difficult for MRI to differentiate operative changes from infection. In these patients, 111In-labeled leukocyte images were more specific than MRI.


Journal of Clinical Gastroenterology | 1998

Hemobilia Due to Hepatic Artery Pseudoaneurysm Thirteen Months After Laparoscopic Cholecystectomy

Alfonso Ribeiro; Hugh J. Williams; Gerald R. May; Jack T. Fulmer; James R. Spivey

Although vascular complications following laparoscopic cholecystectomy are rare, hemobilia may occur within the first 4 weeks after surgery. We report a 57-year-old woman with hemobilia secondary to a pseudoaneurysm of the right hepatic artery presenting 13 months after laparoscopic cholecystectomy. To our knowledge, such late presentation has never before been reported.


Clinical Orthopaedics and Related Research | 1986

Magnetic resonance imaging of osteosarcomas: comparison with computed tomography

William D. Zimmer; Thomas H. Berquist; Richard A. McLeod; Franklin H. Sim; Douglas J. Pritchard; Thomas C. Shives; Lester E. Wold; Gerald R. May

This study was done to describe the magnetic resonance imaging (MRI) characteristics of osteosarcomas and to determine the clinical usefulness of MRI in the evaluation of patients with these tumors. Ten patients with osteosarcomas were examined with a Picker MRI scanner (0.15 Tesla resistive magnet). All had computed tomograms available for comparison. For demonstrating tumor extent in marrow, MRI was superior to computed tomography (CT) in 60% and about equal to CT in 40%. For defining soft tissue mass, MRI was superior to CT in 40% and about equal to CT in 60%. Direct sagittal and coronal images on MRI and superior contrast differences between tumor and normal tissues with MRI were the reasons for the advantage of MRI in these instances. CT was superior in all cases for demonstrating calcifications. Overall, MRI is better than CT for defining local extent of osteosarcomas. It is of greatest value in the peripheral skeleton, in the medullary canal, and in soft tissues.


Mayo Clin., Proc.; (United States) | 1986

Hepatic duct stricture after radical radiation therapy for biliary cancer: Recurrence or fibrosis?

James A. Martenson; Leonard L. Gunderson; Steven J. Buskirk; David M. Nagorney; J. Kirk Martin; Gerald R. May; Claire E. Bender; William J. Tremaine

Two patients with biliary cancer received radical radiation therapy. After treatment, both patients experienced episodes of biliary obstruction without definite evidence of progression of the tumor. These cases emphasize the importance of including radiation-induced biliary fibrosis in the differential diagnosis of hepatic duct stricture after radical radiation therapy.

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