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Biomedical subjects

S E Wilson

Publications and source records attributed to S E Wilson.

At least 145 records · Page 8Linked to original sources
PubMed1996

Intraabdominal abscesses: image-guided diagnosis and therapy.

Intraabdominal abscesses may complicate many illnesses including diverticulitis, pancreatitis, and appendicitis, or they may occur during the postoperative period. As new methods of imaging are developed that provide additional information on patients with these abscesses, earlier and more accurate diagnoses can be made, allowing for prompt intervention. With the advent of these new imaging methods, techniques for treatment of abscesses by percutaneous drainage have been developed. In light of these advances, we review the current strategies for the management of intraabdominal abscesses.

Abdominal Abscess↗
PubMed1996

Prospective study of corneal topographic changes produced by extracapsular cataract surgery.

Cataract surgery is known to induce refractive and corneal astigmatism, but little is known regarding the specific corneal topographic alterations produced by this surgery. We evaluated the corneal topographic effects of extracapsular cataract extraction (ECCE) performed with an 8- to 11-mm posterior limbal incision closed with interrupted sutures and subsequent selective suture removal. Corneal topography was analyzed in 15 eyes with the TMS-1 videokeratoscope preoperatively, before selective suture removal 4-6 weeks after surgery, 2-5 weeks after selective removal of sutures, and at 5 1/2-8 months after surgery. The Surface Regularity Index was significantly increased before suture removal and after suture removal but returned to normal at the final examination. The Irregular Astigmatism Index remained significantly increased at all examinations after surgery. Corneal asymmetry (Surface Asymmetry Index) continued to be significantly increased compared with the preoperative examination after suture removal and at 6 months after surgery. The standard deviation of powers (SDP) was significantly elevated before and immediately after suture removal, but was not significantly different at 6 months. Mean corneal astigmatism remained significantly increased (0.80 +/- 0.11 preoperatively, 1.39 +/- 0.24 at maximum follow-up, p = 0.04). Significant changes in corneal topography occurred in each patient between suture removal and final examinations. A few patients developed against-the-rule astigmatism ranging from 0.6 to 2.2 diopters. ECCE significantly altered corneal tomography compared with the preoperative contour in all patients. In those patients in whom surgically induced nonspherical and noncylindrical distortions occur (radially asymmetrical power distribution, lack of central corneal smoothness), corneal topography may provide information that is useful for management.

Astigmatism↗
PubMed1996

Bilateral popliteal artery injury from bumper crush injury.

Blunt trauma to the knee of sufficient force to result in knee dislocation or fracture is commonly associated with popliteal artery injury. The challenging problem of bilateral popliteal artery injury has been rarely reported. We describe a case of bilateral popliteal artery injury after bumper crush injury between two automobiles that illustrates a successful method of management. Expeditious revascularization with minimum ischemia time was obtained by using the posterior approach, rather than the conventional medial approach, allowing two surgical teams to work simultaneously.

Accidents, Traffic↗
PubMed1996

Hepatocyte growth factor and hepatocyte growth factor receptor in the lacrimal gland, tears, and cornea.

PURPOSE: The purpose of this study was to characterize the expression of hepatocyte growth factor (HGF) and HGF receptor proteins in lacrimal gland, tears, and cornea. METHODS: The reverse transcription-polymerase chain reaction method was used to detect HGF and HGF receptor messenger RNA in human lacrimal gland tissue. HGF and HGF (c-met) receptor monoclonal antibody specificity was demonstrated with fluorescent antibody sorting of cells engineered to express HGF or HGF receptor compared with control cell lines, enzyme-linked immunoadsorbent assay (ELISA), immunoprecipitation, and immunohistology with preabsorption. Immunohistochemistry was applied to study the distribution of HGF and HGF receptor expression in rabbit lacrimal gland tissue and in wounded and unwounded rabbit cornea. An ELISA was used to detect HGF in pooled samples of human tears and individual aliquots of tears collected from patients 1 day after anterior segment surgery. RESULTS: Amplification products of the expected size for HGF and HGF receptor mRNAs were detected in lacrimal tissue and were confirmed to be specific by hot blotting and nucleic acid sequencing. Hepatocyte growth factor protein was detected in interalveolar and interlobular connective tissue cells adjacent to glandular alveolar (acinar) cells and associated with the cells lining the interlobular ducts. Hepatocyte growth factor receptor protein was expressed in the glandular alveolar and interlobular ductal cells in the lacrimal gland and all three cell types of the cornea. It was detected in keratocyte and endothelial cells, and expression was increased in keratocytes after epithelial wounding. Hepatocyte growth factor was not present in corneal epithelial cells, but in the unwounded cornea a strong signal was associated with the epithelial cell surface. It was detected by ELISA in pooled normal tears at levels 186 to 290 pg/ml and in individual postoperative tear samples at 453 to 619 pg/ml. In some tear samples, HGF levels were below the sensitivity of the assay (97.5 pg/ml). CONCLUSIONS: The distribution of HGF receptor protein expression in the lacrimal gland suggests that HGF secreted by interalveolar connective tissue cells traverses the acinar cells and modulates functions in acinar and ductal epithelial cells. Hepatocyte growth factor likely collects within the interlobular ducts and becomes a component in normal tears. Thus, lacrimal gland HGF probably modulates corneal epithelial cell proliferation, motility, and differentiation. Its expression in keratocytes is upregulated after corneal epithelial wounding and probably contributes to the epithelial wound healing process.

Animals↗
PubMed1996

The Fas-Fas ligand system and other modulators of apoptosis in the cornea.

PURPOSE: Previous studies have suggested that the disappearance of anterior keratocytes after injury to the overlying epithelium is mediated by apoptosis. The authors examined the expression of the apoptosis-related modulators, Fas (receptor), Fas ligand, Bax, Bcl-2, Bcl-XL, and interleukin-1 beta converting enzyme (ICE) in corneal cells as candidate mediators of this response and tested the effect of Fas receptor-stimulating antibody on corneal stromal fibroblast cells in vitro. METHODS: Reverse-transcription-polymerase chain reaction was used to detect FAS, FAS ligand, Bax, Bcl-2, Bcl-XL, and ICE mRNA expression in primary cultures of human corneal epithelial, stromal fibroblast, and endothelial cells. Immunohistochemistry was applied to detect Fas and Fas ligand proteins in fresh-frozen sections of normal human cornea. The effect of FAS-stimulating monoclonal antibody on first-passage stromal fibroblasts was studied using a DNA fragmentation assay, the live-dead assay with fluorescent microscopy, toluidene blue staining with light microscopy, and electron microscopy. RESULTS: FAS, Fas ligand, Bax, Bcl-2, Bcl-XL, and ICE mRNAs are expressed in all three major cell types of the cornea. Fas protein is expressed in corneal epithelial, keratocyte, and endothelial cells in fresh-frozen human cornea. Fas ligand protein, however, was detected in corneal epithelial and endothelial, but not keratocyte, cells. Fas-stimulating antibody induced first-passage stromal fibroblast cell death with morphologic changes and DNA fragmentation consistent with apoptosis. CONCLUSIONS: The Fas system (Fas and Fas ligand) modulators and final common pathway mediators of apoptosis are expressed in corneal cells. The distribution of Fas (epithelial, keratocyte, and endothelial cells) and Fas ligand (epithelial and endothelial cells) protein expression in fresh-frozen corneal tissue suggests that Fas ligand expressed in corneal epithelial and endothelial cells modulates functions in keratocyte cells and, possibly, autocrine-juxtacrine functions in epithelium and endothelium. The Fas-Fas ligand system is expressed in the cornea and could have important functions in normal corneal physiology and in the pathophysiology of corneal disease, including modulation of keratocyte apoptosis after epithelial injury.

Amino Acid Sequence↗
PubMed1996

Automated topographic screening for keratoconus in refractive surgery candidates.

PURPOSE: We evaluated an automated corneal topography classification system developed as an adjuvant for screening patients prior to keratorefractive surgery. We screened for patterns suspicious for keratoconus by applying the system to the analysis of a series of patients who presented for evaluation for surgical correction of myopia. METHODS: Both eyes of 53 consecutive patients who were included in a previously reported prospective study were evaluated using the Expert System classification algorithm. This quantitative classification system incorporating eight indices was applied to the videokeratoscopic data from each patient to divide the topographic patterns into keratoconus and non-keratoconus groups. The group assignment of the Expert System classifier was compared with the clinical diagnosis of keratoconus versus non-keratoconus based on the topographic pattern and objective biomicroscopy signs. RESULTS: The Expert System classified eight of the videokeratographs as keratoconus. All five corneas that had clinical evidence of keratoconus were classified as such by the Expert System (sensitivity 100%). The other three corneas that were classified as keratoconus were of patients who wore rigid contact lenses and had pseudo-keratoconus topographic patterns, without other clinical signs of keratoconus. The specificity with which the Expert System detected normal corneas was 97% (98/101). CONCLUSIONS: Evaluation of the videokeratographic data with computerized algorithms designed to detect keratoconus may aid preoperative evaluation and facilitate distinction between keratoconus and some keratoconus-like topographic patterns.

Algorithms↗
PubMed1996

Susceptibility of corneal and conjunctival pathogens to ciprofloxacin.

Ciprofloxacin 0.3% ophthalmic solution has been shown to be effective in the treatment of bacterial keratitis and conjunctivitis, and many physicians use ciprofloxacin as sole therapy in these conditions. In this retrospective study, we found seven of 84 isolates from corneal and conjunctival cultures that were resistant to ciprofloxacin. All of the resistant organisms were gram positive. Six of the isolates (Staphylococcus aureus, Staphylococcus hominis, and four isolates of the Streptococcus viridans group) were from corneal cultures, and one (Staphylococcus aureus) was from a conjunctival culture. Yearly records of systemic isolates from 1988 to 1993 (n = 35,308) demonstrated a statistically significant decrease in susceptibility for several organisms that are common pathogens in the conjunctiva and cornea: Pseudomonas aeruginosa (95-90%, p = 0.001); Staphylococcus aureus (96-87%, p < 0.0001); Staphylococcus spp., coagulase negative (97-81%, p < 0.0001); Enterococcus spp. (92-79%, p < 0.0001); Acinetobacter anitratus (97-77%, p = 0.0006); and Enterobacter cloacae (100-96%, p = 0.03). Although the susceptibility of corneal and conjunctival isolates in this series remained relatively high (91.7%), a much larger series of systemic isolates that are common ocular pathogens revealed a statistically significant increase in resistance to ciprofloxacin over the preceding 5 years.

Anti-Infective Agents↗
PubMed1995

A metal-dependent form of protein phosphatase 2A.

Highly purified bovine heart protein phosphatase 2A catalytic subunit lost virtually all of its activity during storage at -70 degrees. When the enzyme was preincubated with Co2+, over 35% of the original activity was restored. Freshly prepared protein phosphatase 2A purified from bovine heart was stimulated at least 3 to 4-fold by pretreatment with Co2+ or Mn2+. Activation by Co2+ appeared to be irreversible whereas activation by Mn2+ was partially reversed after the cation was chelated with excess EDTA/EGTA. The sensitivity of Co2(+)-stimulated protein phosphatase 2A to okadaic acid or inhibitor-2 was similar to that of spontaneously active protein phosphatase 2A. The enzyme was converted to a latent form by treatment with phosphate or pyrophosphate. The latent form was completely reactivated by preincubation with Co2+. These results demonstrate that protein phosphatase 2A, like phosphatase 1, can exist in a metal ion-dependent form and may represent a new mechanism for the regulation of protein phosphatase 2A activity.

Amino Acid Sequence↗
PubMed1995

Effect of dopamine on renal blood flow and cardiac output.

OBJECTIVE: To characterize the relationship between changes in renal blood flow and cardiac output induced by dopamine, hypothesizing that at low doses renal blood flow changes more than cardiac output. DESIGN: Anesthetized swine had renal blood flow and cardiac output measured during either continuous dopamine infusions (2 to 8 micrograms/kg per minute) or bolus dosing (1 to 16 micrograms/kg), and increases in both were compared. Two different fluid protocols were compared using constant dopamine infusions. In the constant pulmonary capillary wedge pressure protocol, intravenous fluids were titrated to keep this parameter constant. In the other protocol, fluid therapy was held constant at 10 mL/kg per hour. RESULTS: With infusions, mean increases in renal blood flow and cardiac output were relatively equal. The maximum increase was 35% at 8 micrograms/kg per minute under the constant pulmonary capillary wedge pressure protocol, with no significant differences (P > .1) found between the change in renal blood flow and cardiac output at any dose in either protocol. With bolus dosing, renal blood flow increased significantly more than cardiac output at 1, 4, and 8 micrograms/kg (P < .05). CONCLUSION: Disproportionate increases in renal blood flow compared with cardiac output at low bolus doses show initial renal responses to be independent of cardiac output. The infusion data suggest that renal responses exhibit tachyphylaxis or that cardiac output slowly accommodates to decreased total peripheral resistance.

Animals↗
PubMed1995

AIDS and cancer registry linkage: measurement and enhancement of registry completeness. The National AIDS/Cancer Match Study Group.

BACKGROUND AND METHODS: To measure AIDS registry completeness for Kaposi's sarcoma (KS) and cancer registry completeness for KS and non-Hodgkin's lymphoma (NHL), we linked AIDS and cancer registries at selected health departments. RESULTS: We found 10,350 people with KS: 1,935 reported only to the AIDS registry, 1,428 reported only to the cancer registry, and 6,987 reported to both. Ninety-three cases of non-HIV-associated KS were expected. For KS, AIDS registry completeness was 84% [6,987/(6,987 + 1,428 - 93)] and cancer registry completeness was 78% [6,987/(6,987 + 1,935)]. Cancer registry completeness for AIDS-related NHL was 76%. CONCLUSION: If this linking were conducted nationally, about 5,700 additional cases of AIDS and 10,000 additional cases of AIDS-related cancers would be recorded.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Composite porosity of expanded polytetrafluoroethylene vascular prosthesis.

Polytetrafluoroethylene (PTFE) prostheses were modified to produce two types of composite porosity PTFE grafts: type I--inner 60 microns/outer 20 microns and type II--inner 20 microns/outer 60 microns. These composite porosity PTFE designs were investigated for bleed through, graft healing and patency and compared with high porosity PTFE (60 microns) and standard PTFE (20 microns) grafts. The grafts were implanted into the carotid and femoral arteries of dogs and retrieved after 4, 12 and 18 weeks. Both composite porosity grafts showed significantly less bleed through than standard and high porosity grafts after reperfusion. In composite grafts, the 60-microns layer allowed fibrovascular tissue and histiocyte ingrowth from perigraft tissue, but the 20-microns layer did not. Neointima formation occurred earlier and endothelialization was more extensive in high porosity grafts, but seroma formation occurred in 25% of cases. In type I composite porosity grafts, smooth muscle cells of neointima migrated into the pores of the graft, providing a firmly anchored intima. Type II composite porosity grafts allowed better ingrowth of fibrovascular tissue at the outer layer from the perigraft tissue; however, endothelialization was not completed. Composite porosity grafts should be considered for evaluation in specific clinical situations.

Animals↗
PubMed1995

Interferon treatment of Mooren's ulcers associated with hepatitis C.

PURPOSE/METHODS: The cause of Mooren's ulcer is unknown. We examined a patient with chronic hepatitis C who had a corneal ulceration that resembled Mooren's corneal ulcer. RESULTS/CONCLUSION: The corneal ulceration progressed despite appropriate medical and surgical interventions. Recombinant interferon alpha 2b finally led to resolution of the process. The resolution correlated with normalization of the patient's liver function tests. Corneal ulcerations that resemble Mooren's ulcer may be associated with hepatitis C. Recombinant interferon alpha 2b seems to induce remission in the corneal as well as the systemic condition.

Cornea↗
PubMed1995

Managing choledocholithiasis in the laparoscopic era.

BACKGROUND: Management options for common bile duct stones have explained in the era of laparoscopic cholecystectomy (LC), and selecting the most appropriate method for each patient can be problematic due to the difficulty of predicting accurately which patients have choledocholithiasis (CDL). In order to improve selection of appropriate treatment for CDL, treatment options were analyzed for outcome retrospectively during a 25-month period beginning June 1, 1992. PATIENTS AND METHODS: Four hundred four patients underwent LC; 48 (12%) had CDL identified at preoperative endoscopic retrograde cholangiopancreatography (ERCP) or intraoperative cholangiogram (IOCG). Forty-seven patients were referred for preoperative ERCP for suspected CDL, 23 (49%) of whom had proven duct stones and underwent endoscopic sphincterotomy and stone retrieval with an 87% success rate. RESULTS: Of 357 patients scheduled for LC without preoperative ERCP, 236 had IOCG, of which 25 (11%) demonstrated CDL. Seven patients had open common bile duct exploration (CBDE). Sixteen patients had postoperative ERCP after positive IOCG, 7 (44%) of which were positive for CDL and whose stones were removed with 100% success. Two patients were observed, anticipating spontaneous passage of a small stone. CONCLUSIONS: Preoperative ERCP should be applied selectively. For the large majority of patients without preoperative evidence of CDL, we recommend routine IOCG; if CDL is demonstrated, an intraoperative decision can be made to proceed to postoperative ERCP in the usual case or to open CBDE for very large or multiple stones. Observation in anticipation of spontaneous passage may be appropriate for small, solitary common duct stones. Continuing advances in laparoscopic CBDE are likely to reduce further the need to rely on ERCP in managing CDL.

Cholangiography↗
PubMed1995

Redistribution of blood flow after carotid endarterectomy.

PURPOSE: We wanted to characterize the immediate effect of endarterectomy on flow of the arteries composing the extracranial carotid artery system. METHODS: Transit time ultrasound probes were used to measure flow through the carotid bifurcation in 48 patients undergoing endarterectomy. Maximum single-diameter stenosis affecting the internal carotid artery (ICA) was determined by angiography. The significance of differences between means were determined by t tests and analysis of variance; linear and nonparametric correlation analyses were also applied to analyze the relation between stenosis and several flow-derived parameters. RESULTS: Common carotid artery flow significantly increased (p = 0.0043) from a mean value of 264 +/- 99 ml/min to 314 +/- 98 ml/min, corresponding to an average percent increase of 34.3% +/- 71.3%. ICA flow increased from 128 +/- 69 ml/min to 173 +/- 66 ml/min (p < 0.0001), with an average percent increase of 74.9% +/- 114.9%. External carotid artery (ECA) flow decreased from 129 +/- 61 ml/min to 106 +/- 49 ml/min (p = 0.0098), representing an average percent decrease of -5.2% +/- 48.2%. The difference between ECA and ICA mean flow changes is highly significant (p < 0.001). The percent change in ECA flow did not correlate with preoperative stenosis. We noted, however, a positive correlation between stenosis and the ECA/ICA flow ratio before endarterectomy (Spearman r = 0.31, p = 0.032), indicating that more severe stenosis led to a greater distribution of blood into the ECA. The ECA/ICA flow ratio fell from an initial value (ECFbef/ICFbef) of 1.52 +/- 1.74 before endarterectomy to 0.69 +/- 0.37 (ECFaft/ICFaft) after endarterectomy (p = 0.0006). CONCLUSIONS: The data are consistent, with the ECA being an important collateral path for cerebral perfusion when ICA stenosis exists. When endarterectomy relieves bifurcation stenosis, common carotid artery blood flow is redistributed preferentially to the ICA at the expense of ECA flow, consistent with a change in the relative resistances of the two vessels resulting from operative reconstruction.

Blood Flow Velocity↗
PubMed1995

Variability in measurement of abdominal aortic aneurysms. Abdominal Aortic Aneurysm Detection and Management Veterans Administration Cooperative Study Group.

PURPOSE: The purpose of this study was to report interobserver and intraobserver variability of computed tomography (CT) measurements of abdominal aortic aneurysm (AAA) diameter and agreement between CT and ultrasonography observed in the course of a large, multicenter, randomized trial on the management of small AAAs. METHODS: CT measurements of AAA diameter from participating centers were compared with measurements made from the same scan by a central laboratory. Blinded central remeasurement of a randomly selected subset of these CT scans was used to assess intraobserver variability. Agreement between AAA measurements by CT and ultrasonography done within 30 days of each other was also assessed. RESULTS: For interobserver pairs of local and central CT measurements of AAA diameter (n = 806), the difference was 0.2 cm or less in 65% of pairs, but 17% differed by at least 0.5 cm. For intraobserver pairs of central CT remeasurements (n = 70), 90% differed by 0.2 cm or less, 70% were within 0.1 cm, and only one differed by 0.5 cm. Of 258 ultrasound-measured and central CT pairs, the difference was 0.2 cm or less in 44% and at least 0.5 cm in 33%. Ultrasound measurements were smaller than central CT measurements by an average of 0.27 cm (p < 0.0001). Local CT and ultrasound measurements showed a marked preference for recording by half centimeter. CONCLUSIONS: A high degree of precision is possible in CT measurement of AAA diameter, but this precision may not be obtained in practice because of differences in measurement techniques. Differences between imaging modalities increase variability further. Variations in AAA measurement of 0.5 cm or more are not uncommon, and this should be taken into account in management decisions. Efforts to reduce variation in measurement are warranted and might include (1) seeking agreement between surgeons and radiologists on a precise definition of AAA diameter, (2) limiting the number of radiologists who measure AAAs, and (3) use of calipers and magnifying glass for CT measurements.

Aged↗