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Biomedical subjects

D A Owen

Publications and source records attributed to D A Owen.

At least 19 recordsLinked to original sources
PubMed2001

Granular cell tumor of the thyroid.

A case of granular cell tumor of the thyroid gland occurring in a 23-year-old woman is reported. The patient presented with a painless mass in the neck, but was otherwise in good health and had no associated disorders. Fine-needle aspiration biopsy was performed prior to surgery and yielded thyroid epithelial cells with possible oncocytic-type change. To our knowledge, the English language literature contains only one other report of a granular cell tumor of the thyroid. Our case supports the recent suggestion of a neural crest origin for some types of thyroid neoplasia.

Adult↗
PubMed2000

Mesohepatectomy.

BACKGROUND: Formal anatomic (lobar) or extended hepatectomies are recommended for liver malignancies located centrally within the liver (Couinaud's segments IVA, IVB, V, and VIII). Mesohepatectomy, resection of central hepatic segments and leaving the right and left segments in situ, removes large central tumors preserving more functioning liver tissue than either extended left or right hepatectomy. Mesohepatectomy is a seldom used, technically demanding procedure, and its application is yet to be defined. METHODS: Medical charts of 244 consecutive liver resection patients were reviewed retrospectively. Eighteen patients were treated with mesohepatectomy. Six patients had metastatic liver tumor (MLT), 11 had hepatocellular carcinoma (HCC), and 1 had gallbladder adenocarcinoma. The operative results were compared with groups of patients treated by lobar hepatectomy (n = 71) and extended left or right hepatectomy (n = 43). RESULTS: The mean mesohepatectomy operative time was 238 versus 304 minutes in the extended group. Inflow occlusion mean time was longer in the mesohepatectomy group than in extended procedures, 45 versus 39 minutes (P = not significant). Comparing the extended hepatectomy group, the mesohepatectomy group had a mean operative estimated blood loss 914 cc versus 1628 cc (P <0.01), postoperative hospital stay 9 versus 16 days (P = 0.054) and volume of resected liver 560cc versus 1500cc (P <0.01) respectively. The late complication rate was lower in the mesohepatectomy group than in the extended group and was comparable to the lobar hepatectomy group (P = 0.05). CONCLUSIONS: Despite its technical demands, mesohepatectomy should be considered as an alternative to extended hepatectomy for selected patients with primary and secondary hepatic tumors localized in middle liver segments, as its complication rate, postoperative recovery, and preserved liver tissue compare favorably with extended hepatic resection.

Blood Loss, Surgical↗
PubMed2000

Solid-phase synthesis and biological screening of N-alpha-mercaptoamide template-based matrix metalloprotease inhibitors.

A series of N-alpha-mercaptoacetyl containing dipeptides have been prepared on solid-phase supports as putative matrix metalloprotease (MMP) inhibitors. Inhibitor design was based on a positional scanning approach of the amino acids present within a template molecule, previously shown to be an MMP inhibitor with good pharmacological characteristics. This study is the first step in a unique programme, designed to expand the repertoire of molecular templates which can be chosen as starting points for the development of more focused parallel and/or combinatorial libraries of MMP inhibitors as a means to accelerate the lead discovery process. This paper reports the success of such an approach in the development of agents with activity against a number of pathologically important MMPs. After screening of these positional scanning libraries, we have obtained important SAR information, in particular, pharmacophores with the ability to impart selectivity for particular MMP species.

Fluorometry↗
PubMed1999

Electronic imaging and clinical implementation: work group approach at Mayo Clinic, Rochester.

Electronic imaging clinical implementation strategies and principles need to be developed as we move toward replacement of film-based radiology practices. During an 8-month period (1998 to 1999), an Electronic Imaging Clinical Implementation Work Group (EICIWG) was formed from sections of our department: Informatics Lab, Finance Committee, Management Section, Regional Practice Group, as well as several organ and image modality sections of the Department of Diagnostic Radiology. This group was formed to study and implement policies and strategies regarding implementation of electronic imaging into our practice. The following clinical practice issues were identified as key focus areas: (1) optimal electronic worklist organization; (2) how and when to link images with reports; (3) how to redistribute technical and professional relative value units (RVU); (4) how to facilitate future practice changes within our department regarding physical location and work redistribution; and (5) how to integrate off-campus imaging into on-campus workflow. The EICIWG divided their efforts into two phases. Phase I consisted of Fact finding and review of current practice patterns and current economic models, as well as radiology consulting needs. Phase II involved the development of recommendations, policies, and strategies for reengineering the radiology department to maintain current practice goals and use electronic imaging to improve practice patterns. The EICIWG concluded that electronic images should only be released with a formal report, except in emergent situations. Electronic worklists should support and maintain the physical presence of radiologists in critical areas and direct imaging to targeted subspecialists when possible. Case tools should be developed and used in radiology and hospital information systems (RIS/HIS) to monitor a number of parameters, including professional and technical RVU data. As communication standards improve, proper staffing models must be developed to facilitate electronic on-campus and off-campus consultation.

Diagnostic Imaging↗
PubMed1999

Radiofrequency ablation followed by resection of malignant liver tumors.

BACKGROUND: Radiofrequency ablation (RFA) has recently been used to treat liver tumors, but few clinical reports have described the pathological characteristics of radiofrequency ablation in human specimens. This study delineates the gross pathologic and histochemical changes induced by RFA in benign and malignant human liver tissue and confirms the tumor necrosis described in early clinical reports. METHODS: Ten patients with metastatic tumors of the liver received a single treatment of ultrasound-guided percutaneous RFA to 12 tumors. Hepatic resection was carried out within 6 weeks of RFA. Specimens were stained with standard hematoxylin and eosin stain followed by oxidative stain to determine if there was evidence of viable tumor within the zone of ablation. RESULTS: Nine of the 12 ablations were resected. Microscopic examination within the zone of ablation showed successful ablation in 8 of the 9 resected ablations. CONCLUSIONS: Percutaneous RFA creates well-circumscribed areas of tumor necrosis with apparent cell death using an oxidative stain. Further investigation is encouraged to determine the clinical effectiveness of radiofrequency ablation in the complete destruction of liver tumors for palliative or curative intent.

Aged↗
PubMed1999

Occurrence of butyltin residues in sediment and mussel tissues from the lower-most Tennessee River and Kentucky Lake, U.S.A.

Surface sediments and mussel samples were collected at six selected locations in the lower-most Tennessee River and Kentucky Lake, U.S.A. and analyzed for butyltin (BT) derivatives. In sediments, total BT concentrations ranged from 6.8 to 356 ng g-1 dry wt. A wide range of concentrations in sediments suggested the presence of localized area of contamination. In mussel tissues, total BT concentrations varied between 26-107 ng g-1 dry wt. BT levels were comparable to the levels reported in mussels from some coastal sites as well as a few freshwater ecosystems. Leaching of tributyltin-containing anti-fouling paints in the ocean-going ships is a source of tributyltin, and discharge of municipal sewage and industrial waste waters in to this watershed may account for the presence of the monobutyltin and dibutyltin derivatives detected in the samples. To our knowledge, this is the first report on the butyltin concentrations in sediment and mussel tissues from the lower-most Tennessee River and Kentucky Lake.

Animals↗
PubMed1999

Coexisting carcinoid tumors in familial adenomatous polyposis-associated upper intestinal adenomas.

Upper gastrointestinal polyps and extraintestinal tumors are well recognized in association with familial adenomatous polyposis (FAP). Although carcinoid tumors have been reported in association with sporadic colonic neoplasms and ulcerative colitis, to date, carcinoids have not been reported in association with FAP. We report a patient with FAP who has recurrent carcinoid tumors located at the bases of duodenal adenomas. The genetic basis of carcinoid neoplasms is still uncertain. This report may represent the clinical effect of the APC gene mutation on the enterochromaffin cell line manifesting as recurrent carcinoid tumors in physical association with intestinal adenomas. Future genetic analysis and epidemiological studies may be of value in determining whether a true association exists.

Adenoma↗
PubMed1998

Radiofrequency ablation of porcine liver in vivo: effects of blood flow and treatment time on lesion size.

OBJECTIVE: To determine, in vivo, the effect of radiofrequency ablation (RFA) treatment time and tissue blood flow on the size and shape of the resulting necrotic lesion in porcine liver. SUMMARY BACKGROUND DATA: Radiofrequency ablation is an electrosurgical technique that uses a high frequency alternating current to heat tissues to the point of desiccation (thermal coagulation). Radiofrequency ablation is well established as the treatment of choice for many symptomatic cardiac arrhythmias because of its ability to create localized necrotic lesions in the cardiac conducting system. Until recently, a major limitation of RFA was the small lesion size created by this technique. Development of bipolar and multiple-electrode RFA probes has enabled the creation of larger lesions and therefore has expanded the potential clinical applications of RFA, which includes the treatment of liver tumors. A basic understanding of factors that influence RFA lesion size in vivo is critical to the success of this treatment modality. The optimal RFA technique, which maximizes liver lesion size, has yet to be determined. Theoretically, lesion size varies directly with time of application of the RF current, and inversely with blood flow, but these relationships have not been previously studied in the liver. METHODS: Six animals underwent hepatic RFA (460 kHz), for 5, 7.5, 10, 12.5, 15, and 20 minutes. Identical, predetermined anatomic areas of the liver were ablated in each animal. Two additional animals underwent 12 RFA treatments -- 6 with vascular inflow occlusion (Pringle maneuver) and 6 with uninterrupted hepatic blood flow. Animals were euthanized and the livers were removed for gross pathologic examination. All lesions were measured in three dimensions and photographed. Tissues were examined by routine histology and by histochemistry to determine viability. RESULTS: Increasing duration of RFA application from 5 through 20 minutes did not create lesions of larger diameter, but this time increase did predict deeper lesion production (beta = 0.34, p = 0.04). A range of lesion shapes were created from four separate ovals (corresponding to each electrode), to larger ovals intersecting to form a cross, to spheroid lesions. The number of blood vessels in close proximity to the probe tip (within a 1-cm radius from the center of the lesion) strongly predicted minimum lesion diameter (beta = -0.61, p = 0.0001) and lesion volume (beta = -0.56, p = 0.0004). This negative effect of blood flow on lesion size was confirmed experimentally. Radiofrequency ablation lesions created during a Pringle maneuver were significantly larger in all three dimensions than lesions created without a Pringle maneuver: minimum diameter was 3.0 cm (with Pringle) versus 1.2 cm (p = 0.002), maximum diameter was 4.5 cm (with Pringle) versus 3.1 cm (p = 0.002), depth was 4.8 cm (with Pringle) versus 3.1 cm (p < 0.001), and lesion volume was 35.0 cm3 (with Pringle) versus 6.5 cm3 (p < 0.001). CONCLUSIONS: Blood flow is a strong predictor of all RFA lesion dimensions in porcine liver in vivo, whereas a change of treatment time from 5 to 20 minutes is predictive only of lesion depth, but not diameter or volume.

Animals↗
PubMed1998

Inverted Meckel's diverticulum: an entity simulating an ileal polyp.

A case of inverted Meckel's diverticulum is described. This presented as an ileal polyp in an individual with chronic unexplained iron deficiency anemia. Most prolapsed Meckel's diverticula occur acutely as intussusceptions with bowel obstruction and characteristically develop in childhood. This case therefore represents an unusual surgical problem in an older individual in which the diagnosis was clinically unexpected.

Diagnosis, Differential↗
PubMed1998

A novel Alcian yellow-toluidine blue (Leung) stain for Helicobacter species: comparison with standard stains, a cost-effectiveness analysis, and supplemental utilities.

Helicobacter pylori (Hp) gastritis is a worldwide problem significantly associated with duodenal and gastric peptic ulcer disease, gastric carcinomas, and MALT-type lymphomas. A simple, rapid, reproducible, reliable, and inexpensive stain to detect the organism in gastric biopsy specimens is thus of great value. To assess the reliability and cost-effectiveness of a novel Alcian yellow-toluidine blue (Leung) stain for Hp, we stained 60 endoscopic mucosal biopsy specimens from patients with Hp gastritis and measured time to detection of organism, Hp numbers (scale, 1-5), and technical costs. We also stained serial 5-microm step sections of 17 of these cases with the Giemsa and modified Steiner (MS) methods, and similar measurements were made. Also, specimens from various normal gastrointestinal sites and metaplastic lesions, as well as four cases each of giardiasis and cryptosporidiosis, were stained with the Leung method. In the subset of 17 cases, the Leung stain enhanced detection time and compared favorably with the Giemsa method, though the MS method was somewhat superior. Hp scores were similar among all groups. Mean time to detection and Hp scores were similar in the larger (n = 60) group stained with hematoxylin and eosin and the Leung stain. Material costs and technologist's time for Giemsa stains, however, were greater than for the Leung stain, and technologist's time for MS was nearly fourfold that of the Leung stain. With the Leung method, mucus from all gastrointestinal sites and metaplastic lesions stained yellow, and this stain provided excellent contrast and morphologic definition in giardiasis and cryptosporidiosis. We suggest that the newly developed Alcian yellow-toluidine blue (Leung) histochemical stain is a good choice as the standard for routine Hp staining because it is the cheapest and easiest to prepare and because pathologists' detection with this stain compares favorably with detection times achieved with more traditional and established methods.

Coloring Agents↗
PubMed1998

Schwannoma of the pancreas: a report of two cases and a review of the literature.

Schwannoma of the pancreas is a rare neoplasm. It generally affects older adults (average age, 60 yr). The sex incidence is equal. These tumors vary considerably in size and approximately two-thirds are partially cystic, which can cause clinical confusion with epithelial neoplasms. Histologically, they are typical schwannomas, with Antoni A and Antoni B areas, and they do not cause undue diagnostic problems once adequate tissue is examined histologically.

Aged↗
PubMed1997

Massive bleeding from multiple gastric ulcerations in a patient with lymphocytic gastritis and celiac sprue.

Uncontrolled hemorrhage and multisystem organ failure developed in a patient with celiac sprue, lymphocytic gastritis, and diffuse gastric ulceration. A proximal small bowel biopsy showed villous atrophy and lymphoplasmacytic infiltration consistent with celiac sprue. At autopsy, there were no gross or histologic findings to suggest lymphoma. The intestinal lymphocytic infiltrate was not monoclonal, and gene rearrangements were not detected. Lymphocytic gastritis is a rare cause of upper gastrointestinal hemorrhage, which may be the result of sensitivity to gluten or other luminal antigens. This diagnosis should be considered in cases of diffuse gastric ulceration with bleeding in which the endoscopic appearances are not typical of peptic ulcer disease or drug-induced erosions. Ideally, biopsies of gastric and duodenal mucosa should be performed to establish the diagnosis.

Aged↗
PubMed1997

Late recurrent post-transplant primary biliary cirrhosis in British Columbia.

Late recurrent primary biliary cirrhosis (PBC) following orthotopic liver transplant remains a controversial topic. The first documented case of recurrence occurring in 16 patients transplanted for PBC and followed at the authors' institution for longer than one year is presented. A 54-year-old man transplanted for PBC developed a cholestatic pattern of enzyme elevation on post-transplant day (PTD) 1305. Repeat antimitochondrial antibody was strongly positive (1:300 to 1:400). A liver biopsy revealed severe bile duct damage, lymphocytic cholangitis, focal periductal noncaseating granuloma and minimal endotheliitis. Recurrent PBC was diagnosed. At the time of orthotopic liver transplant this patient received induction immunosuppression with OKT3 crossed over to cyclosporine (CsA), azathioprine (AZA) and prednisone. AZA was discontinued early and maintenance CsA tapered to a target trough level of 150 to 200 ng/mL by PTD 365. Prednisone was withdrawn by PTD 664. CsA levels during PTDs 1225 to 1305 (before elevation of hepatobiliary enzymes) were below target at 114 to 166 ng/mL. Of the 16 patients, all but three were maintained on CsA, AZA and prednisone. One was on CsA (trough levels on target) and AZA; the other two, including the patient with recurrent PBC, were on CsA only. The trough CsA level of the patient without recurrent PBC has been within the target range. The authors speculate that the underlying defect in immunoregulation in PBC persists post-transplant and that in the patient without recurrent PBC this defect was unmasked by lowered maintenance immunosuppression--allowing recurrence of PBC in a previously stable liver allograft.

Biopsy, Needle↗