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Biomedical subjects

S E Mitchell

Publications and source records attributed to S E Mitchell.

At least 19 recordsLinked to original sources
PubMed1992

Segmental renal artery embolization for treatment of pediatric renovascular hypertension.

Selective intrarenal arterial embolization was used to treat three children with documented renovascular hypertension. Embolization resulted in complete cure (ie, elimination of all antihypertensive medicines) in all three patients and caused only minimal loss of renal parenchyma. Renal vein renin sampling, including sampling after furosemide administration, correlated well with the location of identified vascular lesions and helped direct selective angiography when lesions were not found initially. Intrarenal arterial embolization is a safe, effective alternative to surgical resection in the treatment of renovascular hypertension in children who have identifiable intrarenal arterial lesions not amenable to balloon angioplasty.

Child↗
PubMed1992

Mitochondrial and ribosomal DNA variation among members of the Anopheles quadrimaculatus (Diptera: Culicidae) species complex.

The extent of intra- and inter-specific variation in mitochondrial DNA and nuclear ribosomal RNA gene restriction sites was determined for the four sibling species of the Anopheles quadrimaculatus complex. Individual mosquitoes were identified by allozyme analysis according to previously published keys, and the total genomic DNA of these same individuals was then cleaved with restriction enzymes. Restriction maps of mitochondrial DNA, including the positions of variable sites, were constructed for each species. No evidence for interspecific hybridization was found in the populations surveyed. There was little variation in restriction patterns within any given species, but differences occurred among the four. Three restriction enzymes (AvaI, HindIII, and PvuII) yielded species-specific DNA restriction patterns for the mitochondrial DNA, while AvaI and HindIII produced diagnostic patterns for the ribosomal DNA. Thus, restriction patterns were very useful for detecting cryptic species but less appropriate than isozymes for studying genetic structure of populations within species.

Animals↗
PubMed1991

Choledochal cysts: role of noninvasive imaging, percutaneous transhepatic cholangiography, and percutaneous biliary drainage in diagnosis and treatment.

Choledochal cysts are an uncommon anomaly of the biliary system; findings include cystic dilatation of the extrahepatic biliary tree, intrahepatic biliary tree, or both. In the past 7 years, 13 patients with choledochal cysts have been seen at the authors' institution for evaluation and presurgical intervention. Percutaneous transhepatic cholangiography (PTC) was performed in 13 patients. Sixteen percutaneous biliary drainage (PBD) procedures were performed in 11 patients, computed tomography was performed in six patients, and ultrasound was performed in two. PTC proved to be an important imaging modality because of its superior ability to define the cyst anatomy, site of biliary origin of the cyst, and extent and detail of both extrahepatic and intrahepatic disease, that is, intraductal strictures and calculi. PBD proved valuable in preoperative intervention, as an aid in surgical reconstruction, and in postoperative care. The role of these two modalities in the diagnosis and treatment of patients with choledochal cysts, in addition to clinical aspects of the disease, is discussed.

Adult↗
PubMed1991

Concurrent radiotherapy and chemotherapy for locally advanced non-small-cell cancer of the lung. Report of a clinical trial and review of the literature.

A prospective nonrandomized phase II study was begun in 1985 using concurrent split-course radiation and chemotherapy in the treatment of locally advanced non-small-cell cancer of the lung. Patients were treated with 3,000 cGy of radiation in 15 fractions to the chest, together with 100 mg/m2 cisplatin on day 1 and 1,000 mg/m2/day 5-fluorouracil infusion on days 1-4. The radiation and chemotherapy were then repeated after a 1-week break. Twenty-one patients were treated, with five patients having a complete response and nine patients having a partial response for an overall response rate of 67%. With a minimum of 24 months follow-up, five patients remain alive. Median survival for the entire group is 11.6 months. The toxicity of the treatment regimen was acceptable. These results do not differ significantly from survivals of similar patients treated with radiation alone, including a series from our own institution. The literature on concurrent chemotherapy and radiation is reviewed and possible future approaches to this tumor are discussed.

Adult↗
PubMed1991

Endoscopy as an adjuvant to biliary radiologic intervention.

Twenty-two patients underwent 24 percutaneous biliary procedures guided with choledochoscopy, an adjunctive percutaneous biliary technique. All but four procedures were performed through established percutaneous tracts; the others, through tracts less than 4 weeks old. The procedures were done for the following reasons: removal of calculi (n = 15), electrohydraulic lithotripsy (n = 1), biliary duct biopsies (n = 8), cauterization of a bleeding tract (n = 1), and evaluation of biliary-enteric anastomoses (n = 11). The only complication was one case of severe nausea after choledochoscopy. This patient required overnight hospitalization and medical treatment. All procedures were technically successful, except one case in which the tract was undersized. All patients received intravenously administered antibiotics before and after the procedure. It is concluded that choledochoscopy is a safe, atraumatic, and well-tolerated method of evaluating and treating biliary disease and that it markedly reduces radiation exposure. It can be performed rapidly with minimal sedation on an in- or outpatient basis.

Adult↗
PubMed1991

Choledochal cysts: classification and cholangiographic appearance.

A classification scheme for choledochal cysts is outlined and their appearance on cholangiograms is illustrated. Choledochal cysts are uncommon anomalies of the biliary system and are probably congenital in origin. They are manifested by cystic dilatation of the extra- or intrahepatic biliary tree or both. The classification system described here divides choledochal cysts into one of five main types. The most common, which is manifested by cystic or focal segmental dilatation of the common bile duct or fusiform choledochal dilatation, accounts for 80-90% of cases.

Cholangiography↗
PubMed1990

Cloning of the mitochondrial genome of Anopheles quadrimaculatus.

The entire 15 kilobase (kb) Anopheles quadrimaculatus mitochondrial DNA (mtDNA) was cloned as three EcoRI fragments in a bacteriophage vector and then subcloned into plasmid vectors. The cloned DNA was physically mapped with restriction endonucleases, and the maps were compared to the restriction patterns of native A. quadrimaculatus mtDNA. Several genes were mapped by sequencing the ends of A. quadrimaculatus mtDNA subclones and by hybridization with the previously characterized Aedes albopictus mtDNA clones. These portions of the genetic map were identical in gene order to those of Drosophila yakuba. The predicted amino acid sequence of the protein coding regions that were sequenced were between 72% and 98% homologous to D. yakuba. The cloned mtDNA will be useful as a probe for population genetic analysis of mosquitoes.

Amino Acid Sequence↗
PubMed1990

Fibrinolytic therapy for upper-extremity arterial occlusions.

Acute upper-extremity arterial occlusion may be due to embolic phenomena or de novo thrombosis. If the occlusion is left untreated, claudication or ischemia necessitating amputation can occur. Operative Fogarty-balloon embolectomy has been the treatment of choice for this entity. In a 6-year period the authors used fibrinolysis on nine occasions in eight patients to treat acute upper-extremity arterial occlusions. Concomitant balloon angioplasty was helpful in four cases. Success, defined as a normal hand with at least one artery that was continuously patent to the wrist, was achieved in all patients. A single significant groin hematoma was seen. Neither stroke nor death occurred in any case, and no amputations were necessary. Local transcatheter intraarterial administration of urokinase can be considered a first-line treatment for brachial artery embolus and other causes of acute upper-extremity arterial occlusion.

Adult↗
PubMed1989

Porcine model for the development of interventional techniques in the gallbladder.

A technique that permits repeated access to the porcine gallbladder through a surgically placed 18 French latex catheter is described and experience with this system in 22 swine is discussed. This porcine gallbladder model produces a reliable and reproducible means for studying clinically applicable interventional procedures.

Abdominal Muscles↗
PubMed1989

Left lobe of the liver: percutaneous biliary drainage.

Left-sided biliary drainage was performed in 89 of 678 (13%) patients undergoing percutaneous biliary drainage procedures during a 9-year period. The most common indication was Klatskin tumor, followed by sclerosing cholangitis, carcinoma of the gallbladder, postoperative benign stricture, and metastasis to the porta hepatis. Left-duct drainage was successful in 82 of the 89 patients (92%) in whom it was attempted. One patient sustained a major hemorrhage from a hepatic artery aneurysm, which was managed with transcatheter embolization.

Bile Ducts↗
PubMed1989

CT of severe renal trauma in children: evaluation and course of healing with conservative therapy.

Over a 2-year period, blunt renal injuries were classified on a four-point scale: grade 1, contusions; grade 2, tears limited to the cortex (renal lacerations); grade 3, tears extending to the collecting system (renal fractures); and grade 4, renal vascular pedicle injuries. We report our findings in nine children with grade 2 and grade 3 blunt renal injuries who were evaluated with CT. One patient had a nephrectomy; the other eight were managed nonsurgically. Six patients had follow-up CT scans 5-19 months later to assess healing. Scars were evident in each case, and the extent of deformity paralleled the magnitude of the initial injury. One patient with a grade 2 injury and two patients with grade 3 injuries healed with small focal scars; three patients with grade 3 injuries healed with large polar scars. In five patients, the CT findings were compared with the findings on 99mTc-DTPA renal imaging. The injured kidneys contributed 30-45% (mean, 38%) of total renal function. In six patients with renal trauma who were treated conservatively, the involved kidneys healed and significant kidney function was preserved, although early surgical intervention might have been beneficial for one of these patients. Prospective studies are needed to evaluate further the effectiveness of this conservative approach.

Child↗
PubMed1988

Streamlining operation of an admitting service for interventional radiology.

The authors describe how operations of an inpatient admitting service for interventional radiology were improved by developing a clinic and hiring a physician's assistant. The service, begun in 1982, was managed by a senior radiologist and fellows. Because of increasing admissions (from a mean of 52 per year in 1982-1985 to 110 per year in 1985-1987), a 1/2-day, twice-weekly clinic was created in 1985 to evaluate new patients and perform follow-up examinations. In 1986 a physician's assistant was hired to assist in the clinic and during patient admissions. Use of the clinic and physician's assistant streamlined patient flow and management during hospitalization. This resulted in a decrease in mean length of stay for patients undergoing angioplasty (from 3.74 days in 1982-1983 to 2.41 days in 1986-1987). This decrease means cost savings for the hospital under the prospective payment system. Other benefits include improved physician-patient relationships and follow-up, new patients for colleagues (15% of patients had anatomy unsuitable for interventional procedures and were referred to staff surgeons), and increased professional fees.

Angioplasty, Balloon↗
PubMed1988

Congenital arteriovenous malformations: tailored embolotherapy.

Congenital arteriovenous malformations (AVMs) involving the pelvis or an extremity were occluded in 16 symptomatic patients, who subsequently underwent tailored embolotherapy. An additional 11 patients did not undergo embolization due to unfavorable vascular anatomy or lack of significant symptoms. Permanent occlusive agents including isobutyl cyanoacrylate, particles of polyvinyl alcohol foam, and coils were used to embolize the multiple feeding vessels and, when possible, the nidus of the AVM. All patients experienced dramatic reduction in pain and resolution of ulceration and bleeding, with a mean follow-up period of 41 months. Symptoms recurred in four patients but again resolved with repeat embolization. The authors conclude that selective and repetitive embolization is highly effective in palliation of symptomatic congenital AVMs.

Adult↗
PubMed1988

Pulmonary arteriovenous malformations: techniques and long-term outcome of embolotherapy.

Over a 10-year period, 276 pulmonary arteriovenous malformations (PAVMs) were occluded with balloon embolotherapy in 76 patients, 67 (88%) of whom had hereditary hemorrhagic telangiectasia. Eleven patients (14%) were discovered by means of family screening with measurement of arterial blood gases and chest radiography. Epistaxis, dyspnea, hemoptysis, and hemothorax occurred in 79%, 71%, 13%, and 9% of patients, respectively. Clinical histories of strokes and transient ischemic attacks were present in 18% and 37% of patients, respectively. Computed tomographic scans of 59 patients showed stroke in 36%. Sixty-five percent of PAVMs were located in the lower lobes, which correlated with the finding of more pronounced hypoxemia in the upright position. After embolotherapy, symptomatic hypoxemia was corrected, and serial values have remained constant for 5 years. Complications were minimal, and no patient required surgery. Balloon embolotherapy is effective long-term therapy for PAVMs, and family screening should be pursued because of the possibility of a higher frequency of paradoxical embolization (stroke) than previously recognized.

Adolescent↗
PubMed1988

Hybridization of laboratory strains of sibling species A and B of Anopheles quadrimaculatus.

Adult mosquitoes of the Anopheles quadrimaculatus complex were collected from Montgomery County, AL (MON) and Alachua County, FL, (KBG) and laboratory stocks of species A and B were established through a selection procedure employing isofemale lines. Progeny from a cross of species B females to ORL males were usually semisterile females and sterile males. Progeny of the reciprocal cross were also semisterile females and sterile males, but the sex ratio was variable and ranged from normal to no males because of male mortality during the pupal stage. Conspecific crosses between strains from the two locations resulted in fertile offspring. Crosses between the sibling species from the two locations invariably gave semisterile females and sterile males (or lethal effects). This evidence confirmed previous data from hybridization and electrophoretic analyses of field populations indicating that Anopheles quadrimaculatus is a species complex.

Animals↗
PubMed1987

The role of CT in the management of pelvic arteriovenous malformations.

Four cases of pelvic arteriovenous malformations (AVM) were diagnosed and managed by CT, angiography, and embolotherapy. CT was used to determine the size, extent, and vascularity of each AVM and the involvement of adjacent organs. Thus CT was pivotal in the choice between surgical extirpation or embolotherapy. CT was also useful in monitoring patients following therapy.

Adult↗
PubMed1987

Long-segment femoropopliteal stenoses: is angioplasty a boon or a bust?

Analysis of 193 femoropopliteal angioplasties demonstrated patency rates in the stenotic group of 75.5% at 6 months and 54.4% at 54 months. The patency rates for the occlusive group were 93.7% at 6 months and 72.9% at 54 months; these rates were significantly better than those in patients with stenoses. A group of 14 patients with long-segment (greater than 7 cm) stenosis had the highest risk of early failure, with a 6-month patency of 23.1%. After removal of the long-segment stenosis group from the results, there were no significant differences between the long-term patencies for stenotic and occlusive lesions. If angioplasty of long stenoses is attempted, a high initial success rate but early failure should be anticipated.

Angioplasty, Balloon↗