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John Thomas

Publications and source records attributed to John Thomas.

At least 19 recordsLinked to original sources
PubMed2006

MR liver imaging and cholangiography in the presence of surgical metallic clips at 1.5 and 3 Tesla.

To evaluate whether clips from prior cholecystectomy impair image quality during magnetic resonance cholangiography (MRC) at 3 Tesla (T) compared with 1.5 T, surgical clips were embedded in a gel phantom and positioned at predefined distances from a fluid-filled tube designed to simulate the bile duct. The maximum clip distance was noted where susceptibility artifacts obscured the fluid-filled tube at 1.5 T and 3 T. Susceptibility artifact size was calculated for each sequence within each magnet class. In vivo analysis included 42 patients postcholecystectomy who underwent MRC at either 1.5 T or 3 T. In vitro, mean area of susceptibility artifacts was 104 mm2 on 3-T and 75 mm2 on 1.5-T MR imaging (MRI). While surgical clips within a 2-mm range impaired visualization of the fluid-filled tube on 1.5-T MRI, this range increased to 4 mm on 3-T MRI. In vivo, MRC image quality was impaired by susceptibility artifacts in three of 21 cases at 3 T and in two of 21 cases at 1.5 T. Overall, biliary pseudo-obstructions due to susceptibility artifacts from cholecystectomy surgical clips were not substantially more common on 3-T MRC in clinical practice, and patients with a history of prior cholecystectomy should not be excluded from a 3-T MRC.

Adult↗
PubMed2006

Beta ig-h3 interacts directly with biglycan and decorin, promotes collagen VI aggregation, and participates in ternary complexing with these macromolecules.

Recombinant human beta ig-h3 was found to bind 125I-labeled small leucine-rich proteoglycans (SLRPs), biglycan, and decorin, in co-immunoprecipitation experiments. In each instance the binding could be blocked by an excess of the unlabeled proteoglycan, confirming the specificity of the interaction. Scatchard analysis showed that biglycan bound beta ig-h3 more avidly than decorin with Kd values estimated as 5.88 x 10(-8) and 1.02 x 10(-7) M, respectively. In reciprocal blocking experiments both proteoglycans inhibited the others binding to beta ig-h3 indicating that they may share the same binding site or that the two binding sites are in close proximity on the beta ig-h3 molecule. Since beta ig-h3 and the SLRPs are known to be associated with the amino-terminal region of collagen VI in tissue microfibrils, the effects of including collagen VI in the incubations were investigated. Co-immunoprecipitation of 125I-labeled biglycan incubated with equimolar mixtures of beta ig-h3 and pepsin-collagen VI was increased 6-fold over beta ig-h3 alone and 3-fold over collagen VI alone. Similar increases were also observed for decorin. The findings indicate that beta ig-h3 participates in a ternary complex with collagen VI and SLRPs. Static light scattering techniques were used to show that beta ig-h3 rapidly forms very high molecular weight complexes with both native and pepsin-collagen VI, either alone or with the SLRPs. Indeed beta ig-h3 was shown to form a complex with collagen VI and biglycan, which appeared to be much more extensive than that formed by beta ig-h3 with collagen VI and decorin or those formed between the collagen and beta ig-h3, biglycan, or decorin alone. Biglycan core protein was shown to inhibit the extent of complexing of beta ig-h3 with native and pepsin-collagen VI suggesting that the glycosaminoglycan side chains of the proteoglycan were important for the formation of the large ternary complexes. Further studies showed that the direct interaction between beta ig-h3 and biglycan and between biglycan and collagen VI were also important for the formation of these complexes. The globular domains of collagen VI also appeared to have an influence on the interaction of the three components. Overall the results indicate that beta ig-h3 can differentially modulate the aggregation of collagen VI with biglycan and decorin. Thus this interplay is likely to be important in tissues such as cornea where such complexes are considered to occur.

Biglycan↗
PubMed2006

Pigtail catheters used for percutaneous fluid drainage: comparison of performance characteristics.

PURPOSE: To compare the performance characteristics of various single-lumen all-purpose pigtail drainage catheters. MATERIALS AND METHODS: The following parameters were compared: flow rates between catheters of the same size, whether changing the fluid viscosity has any effect on catheter comparisons, the effect on flow of leaving an open three-way stopcock in the drainage pathway, the tendency of the catheters to kink, and catheter patency after kinking, as measured according to flow. All-purpose 8.0-, 8.3-, and 8.5-F (collectively referred to as 8-F); 10.0-, 10.2-, and 10.3-F (collectively referred to as 10-F); and 12.0-F pigtail drainage catheters from three manufacturers were evaluated. Data were compared by using two-tailed t tests after normal distributions were confirmed. P < .05 was considered to represent a significant difference. RESULTS: At comparison of the 8-F catheters, the C.R. Bard catheters demonstrated better flow rates than the Cook and Boston Scientific devices. Among the 10-F catheters, there were no significant differences in the flow rates of fluid with viscosity equivalent to that of water between the C.R. Bard and Boston Scientific catheters; however, both these catheter types demonstrated significantly (P < .05) better flow rates than the Cook devices. Among the 12-F catheters, the C.R. Bard catheters demonstrated significantly (P < .05) better flow rates than the other two catheter types. Changing the fluid viscosity caused no changes in comparison results. In all catheter groups, the presence of a stopcock significantly (P < .05) impaired flow. None of the evaluated catheters demonstrated a clear advantage in terms of patency or susceptibility to kinking. CONCLUSION: At comparison of the in vitro performances of catheters from different manufacturers, the C.R. Bard 8.0-F and Cook 10.2-F catheters had comparable flow rates, and flow rates through the C.R. Bard and Boston Scientific 10.0-F catheters were comparable to flow rates through the Cook and Boston Scientific 12.0-F catheters. Varying viscosity had no effect on comparisons of catheter flow rates; however, a stopcock between the vacuum source and the catheter was noted to impair flow rates in all brands and sizes of evaluated catheters.

Catheterization↗
PubMed2006

Postprocedure sepsis in imaging-guided percutaneous hepatic abscess drainage: how often does it occur?

OBJECTIVE: This retrospective study was conducted to determine the incidence of sepsis at our institution after percutaneous drainage of a hepatic abscess. MATERIALS AND METHODS: Thirty-three patients with a hepatic abscess treated using percutaneous aspiration and drainage from 1995 to 2000 were identified from a search of the interventional database. The patients' charts and CT images were reviewed independently by two radiologists for clinical presentation, relevant medical history, pre- and postprocedure antibiotic regimens, and clinical course after percutaneous aspiration and drainage. The preprocedure images were reviewed for the location and morphology of the abscess. The procedure details including percutaneous approach, guidance technique, catheter size, and immediate postprocedure complications were reviewed. RESULTS: Of the 33 patients, 14 patients underwent only needle aspiration of the abscess. In six (43%) of these 14 patients, the abscesses resolved with aspiration and appropriate antibiotic treatment alone. Eight (57%) of the patients who had aspiration of the abscess initially went on to have drainage catheters placed within a 72-hr period. Nineteen patients had drainage catheters placed from the onset. Of these, 17 patients (89%) had abscess resolution. Of the 27 patients who had catheters placed, a total of seven patients (26%) developed clinical symptoms of septicemia after catheter placement, but all patients, at least initially, responded to supportive treatment. Two patients died from septicemia 3-6 weeks after the procedure. None of the patients who underwent aspiration only developed postprocedure septicemia. CONCLUSION: After placement of a percutaneous drainage catheter in a hepatic abscess, there is a significant risk (26%) of postprocedure sepsis. Although it appears to be a random and unpredictable event in our small series, interventional radiologists and referring physicians should be aware of the risk of sepsis after percutaneous drainage of hepatic abscess.

Adult↗
PubMed2005

Small-bowel obstruction: coronal reformations from isotropic voxels at 16-section multi-detector row CT.

PURPOSE: To retrospectively assess the added value of coronal reformations of the abdomen and pelvis from isotropic voxels by using 16-section multi-detector row computed tomography (CT) for the diagnosis of small-bowel obstruction (SBO). MATERIALS AND METHODS: This HIPAA-compliant study was approved by the institutional review board of this medical center with a waiver of informed consent. One hundred consecutive patients (40 men and 60 women; mean age, 55 years) suspected of having SBO and abdominal pain underwent 16-section multi-detector row CT with coronal reformations. Twenty-nine patients had a final diagnosis of SBO, and 71 patients did not. Three independent readers blinded to the diagnosis interpreted the CT scout scan, then transverse scans alone, and then transverse plus coronal scans for the presence of SBO and abnormal wall enhancement. Confidence was scored with a 1-5 scale (1 = absent, 5 = present). RESULTS: Mean sensitivity and specificity of CT scout alone, transverse CT alone, and transverse plus coronal CT for the diagnosis of SBO were 88% and 86%, 87% and 87%, and 87% and 90%, respectively (not significant). In patients without SBO, transverse plus coronal CT enhanced confidence in the exclusion of SBO (P = .01). In patients with SBO, transverse plus coronal CT enhanced confidence in the diagnosis of SBO and identification of abnormal wall enhancement (P = .01). CONCLUSION: Transverse 16-section multi-detector row CT data sets are an excellent test for the diagnosis of SBO, while the addition of coronal reformations obtained from these isotropic data sets adds confidence to the diagnosis and exclusion of SBO.

Adult↗
PubMed2005

Racial differences in pelvic morphology among asymptomatic nulliparous women as seen on three-dimensional magnetic resonance images.

OBJECTIVE: Compare pelvic morphology between asymptomatic African-American and white nulliparous women. STUDY DESIGN: Resting supine T2-weighted magnetic resonance (MR) images were obtained in 12 African-American (AA) and 10 white American (WA) women without pelvic floor dysfunction. Three-dimensional models were reconstructed from the MR images by a masked investigator, and predefined bony and soft tissue pelvic floor parameters were measured and compared. Nonparametric statistics were used, with significance considered at P < .05. RESULTS: Subjects were similar in age and body mass index. Levator ani volume was significantly greater in the AA versus the WA group (mean = 26.8 vs 19.8 cm3, P = .002). The levator-symphysis gap was smaller in the AA (left-18.2, right-18.8 mm) versus the WA group (22.4, 22.6 mm, P = .003, .048) on the left and right. Significant differences were seen in bladder neck position, urethral angle, and the pubic arch angle. CONCLUSION: The increased muscle bulk and closer puborectalis attachment seen among the African-American nulliparous women may impact the development of pelvic floor dysfunction. These findings need further study.

Adult↗
PubMed2005

The prevalence of psoriasis in African Americans: results from a population-based study.

BACKGROUND: Psoriasis is a common disease with substantial effects on quality of life. The prevalence of psoriasis in African Americans has been previously reported as rare. However, there have been no population-based studies to assess the prevalence and burden of psoriasis in African Americans. OBJECTIVE: We sought to measure the prevalence and burden of psoriasis in African Americans compared with Caucasians. METHODS: Patients were randomly selected from the United States population and were asked standard demographic questions. Patients who reported a physician diagnosis of psoriasis were asked additional questions related to quality of life. RESULTS: The total sample included 27,220 individuals of which 21,921 were Caucasian and 2443 were African American. The prevalence of psoriasis was 2.5% in Caucasian patients and was 1.3% in African American patients. African Americans had an approximately 52% reduction in the prevalence of psoriasis compared with Caucasians ( P < .0001). African Americans and Caucasians had similar impacts on quality of life and treatment satisfaction based on single global questions. CONCLUSION: Although psoriasis is less common in African Americans than in Caucasians, it is not rare in either demographic and carries a substantial burden in both groups.

Black or African American↗
PubMed2005

Bacterial biofilms in surgical specimens of patients with chronic rhinosinusitis.

OBJECTIVES: Biofilms are bacterial pathogens that organize in several chronic and recalcitrant infectious processes. We hypothesize that biofilms play a role in chronic rhinosinusitis (CRS). Our goal is to demonstrate biofilms in mucosal specimens of patients undergoing surgery for CRS. STUDY DESIGN: A prospective study of the presence of biofilms in patients undergoing endoscopic sinus surgery for CRS compared with control patients without CRS. METHODS: There were a total of 30 subjects and 4 controls enrolled. The samples of 24 subjects and 4 controls were cultured and then prepared using standard methods for scanning electron microscopy (SEM). The remaining six subjects' samples were treated using advanced cryofixation methods as preparation to preserve structure for SEM and transmission electron microscopy (TEM). RESULTS: Using strict SEM morphologic criteria, 24 (80%) of the 30 patients were found to have micrographic evidence of biofilms. All controls had healthy appearing cilia and goblet cells without biofilms. The six cryofixation samples showed biofilm structures on SEM micrographs that were correlated with bacterial structures seen at the mucosal surface on the corresponding TEM cross sections. Bacterial cultures were positive on all patients. CONCLUSIONS: Biofilms were demonstrated to be present in patients undergoing surgery for CRS; none of the patients without CRS had any evidence of biofilms. Although SEM is capable of demonstrating the biofilms' three-dimensional structure, glycocalyx, and water channels, it cannot clearly demonstrate the presence of bacteria within the biofilm. We were able to demonstrate evidence of bacteria in the biofilms on the subjects tested using TEM.

Adolescent↗
PubMed2004

Low-dose tiagabine effectiveness in anxiety disorders.

BACKGROUND: Gamma-aminobutyric acid (GABA), the predominant inhibitory neurotransmitter of the central nervous system, is involved in the pathophysiology of a wide variety of disorders, including anxiety. Tiagabine hydrochloride acts as a selective GABA reuptake inhibitor (SGRI). METHODS AND RESULTS: Consecutive patients were offered tiagabine in 1-mg incremental doses for the treatment of anxiety, primarily generalized anxiety disorder. Individuals failing anxiety treatment with benzodiazepines, selective serotonin reuptake inhibitors, and buspirone, and/or with a strong family or personal history of substance abuse were allowed trials. The SGRI tiagabine improved anxiety and was well tolerated by adult patients with generalized anxiety disorder as well as one patient with anxiety secondary to acute antidepressant withdrawal. One disinhibition treatment failure is also discussed. CONCLUSION: In acute anxiety treatment, very low initial dosing with gradual increases may be sufficient for anxiety effects, when compared with the higher doses of tiagabine used in epilepsy treatment. Tiagabine may be useful in the treatment of generalized anxiety disorder.

Adolescent↗
PubMed2004

Determinants of quality of life in patients with psoriasis: a study from the US population.

BACKGROUND: Psoriasis is a common disease with substantial effects on quality of life. Few quality of life studies have been performed in psoriasis patients from the general US population. OBJECTIVE: To describe the determinants of quality of life in psoriasis patients from the US population. METHODS: Patients were randomly selected from the US population. Patients who identified themselves as having been diagnosed with psoriasis by a physician were invited to complete a more detailed survey about quality of life. RESULTS: Two hundred sixty-six psoriasis patients from the US population completed the detailed survey. Body surface area showed the strongest association with decrements in quality of life (Spearman 0.50, P < .0001). Younger patients and female patients also had statistically significant reductions in quality of life. Increasing psoriasis severity was associated with seeking care from multiple physicians and having decrements in income. CONCLUSION: Patients with more extensive skin involvement have greater reductions in quality of life. Female patients and young patients are affected to a greater extent.

Age Factors↗
PubMed2004

Multidetector helical computed tomography of the liver: comparison of hepatic enhancement using two different contrast media strategies.

RATIONALE AND OBJECTIVES: The purpose of this study was to compare hepatic enhancement characteristics using two different contrast media injection protocols with multidetector helical computed tomography. MATERIALS AND METHODS: Twenty-three patients with known or suspected liver lesions scheduled to undergo biphasic hepatic multidetector helical computed tomography were randomized into one of two groups: (1) 150 mL of iopamidol (300 mgI/mL) at 5 mL/second, or (2) 100 mL of iopamidol (370 mgI/mL) at 4 mL/second. Unenhanced images were acquired initially, followed by both hepatic arterial phase (scan delay, 33 seconds) and portal venous phase (PVP; scan delay, 65 seconds) imaging. Three abdominal radiologists independently graded the images on a scale from 1-5 for enhancement and overall scan quality. Time-attenuation curves were generated from operator-defined region-of-interest measurements of liver parenchyma and aorta. RESULTS: Qualitatively, the three reviewers found no significant difference between the two study groups in terms of overall scan quality (P = .23) or aortic enhancement (hepatic arterial phase, P = .9; PVP, P = .24). However, liver enhancement during the PVP was considered to be less in the Isovue 370 group (P = .04). Quantitatively, during the hepatic arterial phase, there was no statistically significant difference between the two injection protocols comparing either aortic or hepatic parenchymal enhancement (P = .62 and .80, respectively). During the PVP, these differences were statistically significant, with both aortic and hepatic parenchymal enhancement lower in the Isovue 370 group (P < .01 and P = .04, respectively). CONCLUSION: It is important to consider the amount of iodine injected per second and the duration of the injection when setting up protocols to achieve target organ enhancement. 100 mL of iopamidol 370 at 4 mL/second can be used to obtain images of the liver with good diagnostic quality compared to more conventional protocols using 150 mL of iopamidol 300 at 5 mL/second. However, the degree of liver parenchymal enhancement during the PVP using the latter injection scheme is lower, which in turn could potentially reduce hepatic lesion conspicuity.

Adult↗
PubMed2004

Abdominal aortic aneurysms at multi-detector row helical CT: optimization with interactive determination of scanning delay and contrast medium dose.

PURPOSE: To prospectively evaluate a technique for optimizing aortoiliac enhancement at multi-detector row helical computed tomography (CT) with both the scanning delay and contrast medium dose determined by using an interactive method. MATERIALS AND METHODS: Forty-five patients with abdominal aortic aneurysm were randomized to undergo multi-detector row helical CT with either an interactive protocol (n = 23) or a standard protocol (n = 22). Scanning delays in all patients were determined with automated triggering. Patients in the standard protocol group received 150 mL of contrast medium intravenously at 4 mL/sec. The same injection rate was used for the interactive protocol group, but the dose was reduced with discontinuation of injection at start of scanning. Quantities of contrast medium used and contrast-enhanced aortic attenuation achieved were compared. Aortoiliac enhancement was evaluated qualitatively by using a five-point scale (1 = poor, 5 = excellent). Quantitative and qualitative data were analyzed with the two-tailed t test and Wilcoxon rank sum test, respectively, to determine significance of differences (P <.05). RESULTS: Data from six patients were excluded because of technical errors. Data were analyzed from 20 patients in the interactive protocol group and 19 in the standard protocol group. Mean contrast medium volume was 107 mL +/- 20 (standard deviation) in the interactive protocol group and 148 mL +/- 3 in the standard protocol group (P <.001). Mean contrast-enhanced attenuation at initial, peak, and final measurements was 257 HU +/- 38, 285 HU +/- 46, and 269 HU +/- 54, respectively, for the interactive protocol group, and 261 HU +/- 65, 288 HU +/- 66, and 269 HU +/- 61 for the standard protocol group (P >.05). Mean qualitative enhancement scores for interactive and standard protocol groups were 4.47 and 4.44, respectively (P =.47). CONCLUSION: The interactive method is a simple, efficient, and reproducible way to optimize aortoiliac enhancement while reducing contrast medium dose.

Aged↗
PubMed2003

Epratuzumab, a humanized monoclonal antibody targeting CD22: characterization of in vitro properties.

PURPOSE: Epratuzumab is a novel humanized antihuman CD22 IgG1 antibody that has recently shown promising clinical activity, both as a single agent and in combination with rituximab, in patients with non-Hodgkin's lymphomas (NHL). In an attempt to better understand the mode of action of epratuzumab, the antibody was tested in vitro in a variety of cell-based assays similar to those used to evaluate the biological activity of other therapeutic monoclonal antibodies, including rituximab. In this report, we present epratuzumab activities as they relate to binding, signaling, and internalization of the receptor CD22. METHODS: Chinese hamster ovary-expressed CD22 extracellular domain was used to measure epratuzumab affinity on Biacore. CD22 receptor density and internalization rate were measured indirectly using a monovalently labeled, noncompeting (with epratuzumab) anti-CD22 antibody on Burkitt lymphoma cell lines, primary B cells derived from fresh tonsils, and B cells separated from peripheral blood samples obtained from patients with chronic lymphocytic leukemia or healthy volunteers. Epratuzumab-induced CD22 phosphorylation was measured by immunoprecipitation/Western blot and compared with that induced by anti-IgM stimulation. RESULTS: Epratuzumab binds to CD22-extracellular domain, with an affinity of K(D) = 0.7 nM. Binding of epratuzumab to B cell lines, or primary B cells from healthy individuals and patients with NHL, results in rapid internalization of the CD22/antibody complex. Internalization appears to be faster at early time points in cell lines than in primary B cells and NHL patient-derived B cells, but the maximum internalization reached is comparable for all B cell populations after several hours of treatment and appears to reach saturation at antibody concentrations of 1-5 micro g/ml. Finally, epratuzumab binding results in modest but significant CD22 phosphorylation. CONCLUSIONS: Epratuzumab represents an excellent anti-CD22 ligating agent, highly efficacious in inducing CD22 internalization, and can induce phosphorylation. Although we cannot unequivocally demonstrate here that epratuzumab-induced internalization and signaling of CD22 directly contribute to its therapeutic efficacy, these properties are the fundamental characteristics of the target CD22 and its interaction with epratuzumab. Similar results were observed when epratuzumab was tested in vitro on Burkitt B cell lines as well as on primary normal B cells and neoplastic B cells separated from fresh peripheral blood samples from patients with chronic lymphocytic leukemia.

Animals↗