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R C Nelson

Publications and source records attributed to R C Nelson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Activated lymphocytes promote endothelial cell detachment from matrix: a role for modulation of endothelial cell beta 1 integrin affinity.

In vivo, MHC class I-restricted injury of allogeneic tissue or cells infected by intracellular pathogens occurs in the absence of classical cytolytic effector mechanisms and Ab. Modulation of the target cell adhesion to matrix may be an additional mechanism used to injure vascular or epithelial cells in inflammation. We studied the mechanisms of human umbilical vein endothelial cell (EC) detachment from matrix-coated plastic following contact by concanamycin A-treated lymphocytes as an in vitro model of perforin-independent modulation of EC basement membrane adhesion. Human PBL were depleted of monocytes, stimulated, then added to an EC monolayer plated on either fibronectin or type I collagen matrices. Activated, but not resting, PBL induced progressive EC detachment from the underlying matrix. Injury of the EC monolayer required direct cell contact with the activated lymphocytes because no detachment was seen when the PBL were placed above a Transwell membrane. Moreover plasma membranes prepared from activated but not resting PBL induced EC detachment. Adherent EC stimulated with activated PBL did not show evidence of apoptosis using TUNEL and annexin V staining at time points before EC detachment was observed. Finally, neither the matrix metalloproteinase inhibitors o-phenanthroline and BB-94 nor aprotinin blocked EC detachment. However, activation of EC beta1 integrin using mAb TS2/16 or Mg2+ decreased EC detachment. These data indicate that cell-cell contact between activated PBL and EC reduces adhesion of EC to the underlying matrix, at least in part by inducing changes in the affinity of the endothelial beta 1 integrin.

Adjuvants, Immunologic↗
PubMed1999

Fine-needle aspiration with flow cytometric immunophenotyping for primary diagnosis of intra-abdominal lymphomas.

Cytomorphology in conjunction with immunophenotypic characterization is becoming increasingly used for the primary diagnosis of non-Hodgkin's lymphomas (NHL). This combination is especially advantageous for the diagnosis of intra-abdominal and intrathoracic lymphomas, since unlike superficial lesions, open biopsy of deep-seated tissues is more invasive and more costly, and is associated with a higher risk. We report the cytologic and immunophenotypic features of intra-abdominal NHL obtained by fine-needle aspiration (FNA). Twenty-two cases of intra-abdominal lesions obtained by image-guided FNA where flow cytometry was also performed were reviewed. Of the 22 studied cases, 7 were classified as large-cell lymphoma, 5 as follicular center-cell lymphoma, 2 as small noncleaved-cell lymphoma, 2 as lymphoplasmacytoid lymphoma, one as small lymphocytic lymphoma, and one as marginal-zone lymphoma. In the remaining 4 cases where the immunophenotypic pattern was not definitive, the cytomorphologic features were of small cleaved cells in 3 cases and of mixed small cleaved and large cells in one case. We successfully classified 9 of the 10 patients on whom histologic confirmation was obtained. The successful primary classification of most intra-abdominal non-Hodgkin's lymphomas can be done with a combination of cytology and flow cytometry, and this can be the initial approach in patients with deep-seated lesions. Diagn. Cytopathol. 1999;21:98-104.

Abdominal Neoplasms↗
PubMed1999

Extravasation detection accessory: clinical evaluation in 500 patients.

PURPOSE: To assess the ability of an extravasation detection accessory (EDA) to detect clinically important (> or = 10 mL) extravascular injection of iodinated contrast material delivered with an automated power injector. MATERIALS AND METHODS: Five hundred patients referred for contrast material-enhanced body computed tomography (CT) participated in a prospective, multi-institutional, observational study in which the EDA was used to identify and interrupt any injection associated with clinically important extravasation. The presence or absence of extravasation was definitively established with helical CT at the injection site (injection rate, from 1.0 to 5.0 mL/sec; mean, 2.9 mL/sec; median, 3.0 mL/sec). RESULTS: There were four true-positive (extravasation volumes, 13-18 mL), 484 true-negative, 12 false-positive, and no false-negative cases. The prevalence of overall and clinically important (> or = 10 mL) extravasation was 3.6% (18 of 500 cases) and 0.8% (four of 500 cases), respectively. The EDA had a sensitivity of 100% (four of four cases; 95% CI: 51%, 100%) and a specificity of 98% (484 of 496 cases; 95% CI: 96%, 99%) in the detection of clinically important extravasation. CONCLUSION: The EDA is easy to use, safe, and accurate in the monitoring of intravenous injections for extravasation, which could prove especially useful in high-flow-rate CT applications.

Contrast Media↗
PubMed1999

Multiple fluid collections: CT- or US-guided aspiration--evaluation of microbiologic results and implications for clinical practice.

PURPOSE: To determine if patients with multiple fluid collections need every collection aspirated and if cross-contamination is a risk if separate sterile procedures are not followed for each aspiration. MATERIALS AND METHODS: Records from 1,076 imaging-guided percutaneous aspirations and drainages over 39 months were retrospectively reviewed; 124 patients had multiple fluid collections drained, which yielded 287 aspirates. The patients were divided into two groups: those (n = 82) with multiple collections aspirated on any 1 day, and those (n = 61) with multiple collections aspirated over 10 days. Nineteen patients were included in both groups. Gram stain microscopy and culture results were compared between sequential aspirates in each patient, and their potential effects on antimicrobial therapy and theoretic risk for cross-contamination were evaluated. RESULTS: In 82 patients undergoing multiple aspirations on any 1 day, multiple microorganisms differed in 32 patients, which indicated a need for therapy change in 18 (22%) patients. In 61 patients undergoing aspiration on different days, microorganisms differed in 32 patients, which indicated a need for therapy change in 15 (25%) patients. Cross-contamination could have occurred in 28 of 93 (30%) aspirates from patients with a second or subsequent collection if separate sterile procedures had not been undertaken. CONCLUSION: When multiple fluid collections are identified, aspirates from all collections should be obtained through separate sterile procedures to ensure optimal antimicrobial coverage and avoid cross-contamination.

Adult↗
PubMed1999

Imaging-guided percutaneous biopsy of focal splenic lesions: update on safety and effectiveness.

OBJECTIVE: The purpose of this study is to determine the safety and effectiveness of percutaneous imaging-guided biopsy in the diagnosis of focal splenic lesions. MATERIALS AND METHODS: From May 1995 to November 1997, 20 imaging-guided biopsies of focal splenic lesions were performed in 18 patients, including seven patients with a prior diagnosis of extrasplenic malignancy (breast cancer, n = 3; lymphoma, n = 2; ovarian cancer, n = 1; and osteogenic sarcoma, n = 1), three immunosuppressed patients (cause of immunosuppression: AIDS, n = 1; liver transplantation, n = 1; and bone marrow transplantation, n = 1), two patients with anemia, one patient with a recent history of IV drug abuse, and five patients with incidentally discovered splenic lesions. Biopsies were performed with an 18-gauge (n = 1), a 20-gauge (n = 8), or a 22-gauge (n = 14) self-aspirating needle or an 18-gauge cutting needle (n = 1). Biopsies were considered successful if a specific diagnosis of benign or malignant disease was made. RESULTS: A specific diagnosis was made in 16 (88.9%) of 18 patients, and no complications occurred. Malignancy was diagnosed in six patients including three patients with lymphoma. Benign conditions were diagnosed in 10 patients: a cyst in two patients; hamartoma in one; lipogranuloma in one; infarct in one; and infection in four, including one case each of Candida albicans, Pneumocystis carinii, Mycobacterium tuberculosis, and mixed flora. The tenth benign diagnosis was a pseudotumor of the spleen related to a bulbous tail of the pancreas that was inseparable from the splenic hilum. Biopsy did not establish a diagnosis in one patient with lymphoma and in one patient with presumed splenic candidiasis. A mean of 1.5 needle passes was made per biopsy. CONCLUSION: Imaging-guided splenic biopsy is a safe technique that provides a specific diagnosis in most patients with focal splenic lesions.

Adult↗
PubMed1999

Comparison of unenhanced, hepatic arterial-dominant, and portal venous-dominant phase helical CT for the detection of liver metastases in women with breast carcinoma.

OBJECTIVE: The purpose of this study was to evaluate triple-phase helical CT for detection of hepatic metastases from breast carcinoma. SUBJECTS AND METHODS: Breast cancer patients were studied prospectively with triple-phase helical CT in 300 consecutive examinations. Hepatic arterial-dominant and portal venous-dominant phase scans were initiated at 20 and 65 sec, respectively, after IV injection of 175 ml of iopamidol (30 mg/ml) at 5 ml/sec. Three independent observers each reviewed 200 cases of the portal venous-dominant phase for lesion number, conspicuity, and attenuation. Subsequently, portal venous-dominant phase images were reevaluated in conjunction with hepatic arterial-dominant phase or unenhanced images. RESULTS: Hepatic metastases were identified in 79 (26%) of 300 cases. Lesions detected on portal venous-dominant, hepatic arterial-dominant, and unenhanced images were as follows: observer 1, n = 198, 164, and 171; observer 2, n = 254, 233, and 233; and observer 3, n = 291, 270, and 276 (p > .05). The mean total lesion count was 387, with more lesions detected on portal venous-dominant phase than on either hepatic arterial-dominant phase or unenhanced images (p < .001 and p < .0001, respectively). For individual observers, 10-26% of lesions were hypervascular on hepatic arterial-dominant phase images. Two to 4% of lesions were identified only on hepatic arterial-dominant phase or unenhanced images. However, in these few cases, the lesions either were false-positives or were seen in conjunction with additional metastases on portal venous-dominant images. CONCLUSION: Routine use of triple-phase CT in patients with breast carcinoma may not be warranted: Addition of the hepatic arterial-dominant phase or unenhanced images revealed few additional lesions in our group of 300 patients.

Adult↗
PubMed1999

Indeterminate findings on imaging-guided biopsy: should additional intervention be pursued?

OBJECTIVE: Our purpose was to determine the outcome of patients in whom the results of imaging-guided biopsies were indeterminate and to examine factors that may affect outcome. MATERIALS AND METHODS: During a 25-month period, 619 consecutive imaging-guided biopsies (CT, n = 268 [43%]; sonography, n = 351 [57%]) were performed on abdominal lesions. Of these biopsies, findings from 454 biopsies (73%) were positive for malignancy, findings from 21 biopsies (3%) yielded a benign diagnosis, and findings from 15 biopsies (2%) were nondiagnostic. Findings from the remaining 129 biopsies (21%) were considered indeterminate because the pathologic diagnosis revealed benign tissue, inflammation, stromal elements, or atypical cells. The frequency of malignancy in lesions of patients in this indeterminate group was determined. RESULTS: Thirty-eight of the 129 patients were lost to follow-up. Of the remaining 91 patients, 55 (60%) had true-negative (benign) results, and 36 (40%) had false-negative (malignant) results. A history of malignancy had no significant effect on the true- or false-negative rate (p = .799). However, the guidance technique had a statistically significant effect: CT and sonographic guidance yielded 25 (49%) and 11 (28%) false-negative results, respectively (p = .037). The number of needle passes, needle type and gauge, and biopsy site did not have a statistically significant correlation with the false-negative rate. The presence of atypical cells in the cytologic aspirate was highly predictive, with a 71% false-negative rate (p = .008). CONCLUSION: We found a high incidence of malignancy (40%) in lesions deemed indeterminate at the time of biopsy. Thus, close follow-up or additional intervention should be pursued in such cases. Sonographic guidance resulted in a statistically significant decrease in the false-negative rate when compared with CT guidance; however, a history of malignancy, the biopsy site, the needle gauge and type, and the number of passes did not have a significant effect on the false-negative rate.

Biopsy, Needle↗
PubMed1999

PACS in sonography: accuracy of interpretation using film compared with monitor display. Picture archiving and communication systems.

OBJECTIVE: The goal of this study was to determine the relative accuracy of interpretation of sonography when viewed on a monitor or on film. MATERIALS AND METHODS: Four radiologists twice interpreted a series of 440 sonograms using the following sequences of display formats for initial and second interpretations: film-film, film-monitor, monitor-film, and monitor-monitor. Reporting discrepancies between the initial and subsequent interpretation were reviewed by an arbitration panel unaware of the display mode. Results were analyzed for differences in error rate attributable to film versus monitor display format, chronology of interpretation, individual observer, and observer seniority. RESULTS: We found no statistically significant difference in the error rate for film (10.3%) versus monitor display format (14.6%) (p = .09). Likewise, we found no significant differences in the error rates attributable to chronology of interpretation (p = .13), individual observer (p = .54), or observer seniority (p = .87). CONCLUSION: Interpretative accuracy is similar whether sonograms are interpreted on a monitor or on film.

Artifacts↗
PubMed1999

Percutaneous liver biopsy: a cost-benefit analysis comparing sonographic and CT guidance.

OBJECTIVE: We compared the relative cost of a liver biopsy performed with sonographic guidance with that of one performed with CT guidance in a cost-benefit analysis model. MATERIALS AND METHODS: Variables were estimated from a search of the literature and from clinical experience with 437 hepatic biopsies at our institution. Probability variables included the probability of obtaining an adequate sample and the probability of a major complication. Cost variables included the direct and indirect costs, the cost of a major complication, and the opportunity costs of foregone revenue from preempted diagnostic studies. One-way and two-way sensitivity analyses were performed. RESULTS: Using baseline values, CT guidance was 1.89 times more expensive than sonographic guidance. Sensitivity analyses indicate that CT and sonographic guidance costs would be equivalent if the success rate with sonographic guidance was 39.8%, the opportunity costs of CT guidance were 3.13 times less than best estimates, and the opportunity costs of sonography were 3.15 times greater than best estimates. CONCLUSION: Sonographic guidance for hepatic biopsies is substantially more economical than CT guidance across a wide range of estimated costs.

Biopsy, Needle↗
PubMed1999

Neonatal porcine islet cells induce human CD4+, but not CD8+, lymphocyte proliferation and resist cell-mediated cytolytic injury in vitro.

Xenotransplantation of porcine tissue to human recipients promises to alleviate the organ shortage. Human antibody-mediated and cell-mediated immune responses against porcine grafts, however, represent barriers to successful xenotransplantation. We compared neonatal porcine islet cells (NPICs) and neonatal porcine splenocytes for the ability to stimulate proliferation of human peripheral blood lymphocytes (PBLs), and for their susceptibility to human natural killer (NK) and cytotoxic T-lymphocyte (CTL)-mediated lysis. Human peripheral blood CD4+ lymphocytes showed strong proliferation in response to NPICs, likely because of occasional swine leukocyte antigen (SLA) class II+ cells in the NPIC preparations. In contrast, human peripheral blood CD8+ lymphocytes did not proliferate in response to NPICs, although they showed clear responses to both porcine splenocytes and endothelial cells. Both human CTL-raised-against-porcine splenocytes and endogenous NK cells lysed porcine splenocytes, but the same cells showed little or no lytic activity against NPICs. Lysis of porcine splenocyte targets was completely abrogated by pretreatment of the human NK or CTL populations with concana-mycin A, suggesting a perforin-dependent effector mechanism. Pretreatment of the NPIC targets with proinflammatory porcine cytokines to upregulate SLA class I expression failed to enhance human CTL-mediated lysis. However, lysis of NPICs by human CTLs could be elicited when a lectin was added to form stable effector:target cell conjugates. It appears that NPICs do not express sufficiently high levels of co-stimulatory and/or adhesion molecules to either activate human CD8+ T-cells or to be effective targets for activated human CTLs. These data suggest that NPICs may not be destroyed by NK- or CTL-mediated lytic mechanisms after transplantation into humans.

Animals↗
PubMed1998

Large-scale tests of a keyed, appearance-based 3-D object recognition system.

We describe and analyze an appearance-based 3-D object recognition system that avoids some of the problems of previous appearance-based schemes. We describe various large-scale performance tests and report good performance for full-sphere/hemisphere recognition of up to 24 complex, curved objects, robustness against clutter and occlusion, and some intriguing generic recognition behavior. We also establish a protocol that permits performance in the presence of quantifiable amounts of clutter and occlusion to be predicted on the basis of simple score statistics derived from clean test images and pure clutter images.

Computer Simulation↗
PubMed1998

Disseminated thrombosis in primary antiphospholipid syndrome: MR findings.

We report the MR imaging findings in a patient with primary antiphospholipid syndrome, adrenal infarction and widespread thrombosis involving abdominal, pelvic, and pulmonary vessels. This syndrome should be suspected in patients with thromboses and organ infarctions of otherwise undetermined etiology.

Adrenal Glands↗
PubMed1998

Predictive model for the diagnosis of intraabdominal abscess.

RATIONALE AND OBJECTIVES: The authors investigated the use of an artificial neural network (ANN) to aid in the diagnosis of intraabdominal abscess. MATERIALS AND METHODS: An ANN was constructed based on data from 140 patients who underwent abdominal and pelvic computed tomography (CT) between January and December 1995. Input nodes included data from clinical history, physical examination, laboratory investigation, and radiographic study. The ANN was trained and tested on data from all 140 cases by using a round-robin method and was compared with linear discriminate analysis. A receiver operating characteristic curve was generated to evaluate both predictive models. RESULTS: CT examinations in 50 cases were positive for abscess. This finding was confirmed by means of laboratory culture of aspirations from CT-guided percutaneous drainage in 38 patients, ultrasound-guided percutaneous drainage in five patients, surgery in five patients, and characteristic appearance on CT scans without aspiration in two patients. CT scans in 90 cases were negative for abscess. The sensitivity and specificity of the ANN in predicting the presence of intraabdominal abscess were 90% and 51%, respectively. Receiver operating characteristic analysis showed no statistically significant difference in performance between the two predictive models. CONCLUSION: The ANN is a useful tool for determining whether an intraabdominal abscess is present. It can be used to set priorities for CT examinations in order to expedite treatment in patients believed to be more likely to have an abscess.

Abdominal Abscess↗
PubMed1998

Fine-needle aspiration of gastrointestinal stromal tumors.

Gastrointestinal stromal tumors are a group of neoplasms encompassing leiomyoma, leiomyosarcoma, and an epithelioid variant of leiomyosarcoma, as well as lesions expressing neural differentiation. These neoplasms are rare and account for 1% of all gastrointestinal tumors. With increasing frequency, fine-needle aspiration (FNA) has been used to diagnose intra-abdominal neoplasms before institution of definitive treatment. We encountered four patients with gastrointestinal stromal tumors diagnosed by FNA who ultimately underwent surgical excision of their tumors. The age of the patients ranged from 57 to 88 years. Smears from the aspirates were cellular and consisted of numerous small spindle cells distributed as cohesive fragments and individual cells. The dispersed cell population appeared largely as stripped nuclei. Several nuclei had perinuclear or paranuclear vacuoles, similar to the "halos" seen in sections. Cytologic evidence of malignancy (pleomorphism, nuclear irregularity, mitoses) were not identified in smears. Corresponding histologic sections demonstrated varying degrees of malignancy ranging from benign or low grade to frankly sarcomatous gastrointestinal stromal tumors. We conclude that the diagnosis of gastrointestinal stromal tumors can be made with a certain degree of confidence by using FNA findings. However, predictions about potential aggressiveness are best reserved for gross and histologic examination of the resected specimen.

Aged↗
PubMed1998

Carcinoid metastases to the liver: role of triple-phase helical CT.

PURPOSE: To evaluate triple-phase helical computed tomography (CT) of carcinoid liver metastases. MATERIALS AND METHODS: Triple-phase helical CT was performed in 31 patients with proved carcinoid liver metastases. Hepatic arterial-dominant phase (HAP) and portal venous-dominant phase (PVP) images were obtained 20 and 70 seconds after intravenous iopamidol injection. Four independent readers reviewed each phase for lesion number, conspicuity, and attenuation relative to liver. Three readers reviewed each phase to determine which phase best showed the lesions. RESULTS: The lesions detected by readers 1-4 were as follows: noncontrast phase, 164, 177, 204, and 229 lesions; HAP, 178, 177, 214, and 238 lesions; and PVP, 180, 189, 215, and 250 lesions (P > .05). On HAP images, readers found that 80, 73, 96, and 102 lesions were hyperattenuating. Consensus indicated there were 206 focal lesions. Of these 206 lesions, 72, 72, and 62 lesions were best seen on the noncontrast phase, HAP, and PVP images, respectively. Six, 28, and six lesions were seen only on the noncontrast phase, HAP, and PVP images, respectively. Two patients had lesions seen only on the HAP images. CONCLUSION: The HAP and, to a lesser extent, the noncontrast phase provide added value in evaluating carcinoid liver metastasis.

Carcinoid Tumor↗