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Biomedical subjects

J Yee

Publications and source records attributed to J Yee.

At least 19 recordsLinked to original sources
PubMed2005

Risk of bleeding and restenosis among chronic kidney disease patients undergoing percutaneous coronary intervention.

BACKGROUND: Bleeding risk is increased in renal failure due to impaired platelet adhesiveness. Patients who undergo percutaneous coronary intervention (PCI) are given multiple antiplatelet agents that increase that risk. We retrospectively tested the hypothesis that chronic kidney disease (CKD) patients who undergo PCI are at higher risk of bleeding and restenosis (due to chronic inflammation) compared to patients with normal renal function. METHODS: Patients who had PCI for non-ST elevation myocardial infarction or unstable angina between July 2001 and June 2003 (1,184 patients) were included in the study. All the patients were given periprocedural clopidogrel, aspirin and glycoprotein IIb/IIIa inhibitor if indicated, and then continued on clopidogrel and aspirin daily for 12 months. The patients were classified into 5 groups according to the CKD stage and followed-up for 12 months for development of major or minor bleeding, restenosis, length of hospital stay and survival. RESULTS: The incidence of major bleeding within the first month (3.4% in normal kidney function patients (Gp 1), 4.8% for CKD Stages 1 and 2 patients (Gp2), 5.2% for CKD Stage 3 patients (Gp3), 6.1% for CKD Stage 4 patients (Gp4) and 9.3% for CKD Stage 5 patients (Gp5), p = 0.001) and for minor bleeding (5.7% in Gp1, 6.5% for Gp2, 7.4% for Gp3, 9.2% for Gp4 and 11.3% for Gp5, p = 0.001) and the incidence of restenosis at one month (4.6% in Gp1, 5.3% for Gp2, 6.8% for Gp3, 7.3% for Gp4 and 9.6% for Gp5, p = 0.001) and 6 months (11.2% in Gp1, 13.5% for Gp2, 15.7% for Gp3, 16.4% for Gp4 and 19.7% for Gp5, p = 0.001) were higher with worsening CKD. Survival at one year was worse with worsening of the kidney function. CONCLUSION: Worsening of CKD is associated with progressively increased risk of minor and major bleeding, restenosis and death during and after PCI.

Analysis of Variance↗
PubMed2004

Gastrointestinal infection in the immunocompromised (AIDS) patient.

In the past two decades acquired immunodeficiency syndrome (AIDS) has become one of the most devastating illnesses in human history. As the epidemic continues to spread increasingly, AIDS patients are no longer confined to a few specialized AIDS hospitals and are now seen in general hospitals and clinics everywhere. Radiologists need to recognize the appearances, to understand how-safely-to care for patients with this disease, and to know enough about the illness to be able to counsel their patients. This article presents a review of current knowledge about the wide range of gastrointestinal hepatic, splenic, biliary, and retroperitoneal manifestations in AIDS, and how the role of modern medical imaging techniques and diagnosis and treatment can be applied. The imaging aspects (conventional double-contrast gastrointestinal studies, ultrasound, CT, and MR) of the diseases of the luminal gastrointestinal tract, liver, spleen, biliary tract, and retroperitoneum will be systematically discussed. Candidiasis, herpes, cytomegalovirus, cryptosporidiosis, histoplasmosis, isosporiasis, salmonellosis, toxoplasmosis, unusual mycobacteria, and viral infections account for the majority of non-neoplastic disorders.

AIDS-Related Opportunistic Infections↗
PubMed2004

Compliance with the CONSORT checklist in obstetric anaesthesia randomised controlled trials.

The Consolidated Standards for Reporting of Trials (CONSORT) checklist is an evidence-based approach to help improve the quality of reporting randomised controlled trials. The purpose of this study was to determine how closely randomised controlled trials in obstetric anaesthesia adhere to the CONSORT checklist. We retrieved all randomised controlled trials pertaining to the practice of obstetric anaesthesia and summarised in Obstetric Anesthesia Digest between March 2001 and December 2002 and compared the quality of reporting to the CONSORT checklist. The median number of correctly described CONSORT items was 65% (range 36% to 100%). Information pertaining to randomisation, blinding of the assessors, sample size calculation, reliability of measurements and reporting of the analysis were often omitted. It is difficult to determine the value and quality of many obstetric anaesthesia clinical trials because journal editors do not insist that this important information is made available to readers. Both clinicians and clinical researchers would benefit from uniform reporting of randomised trials in a manner that allows rapid data retrieval and easy assessment for relevance and quality.

Adult↗
PubMed2004

The potential role of statins in contrast nephropathy.

BACKGROUND: Administration of contrast agents may result in an acute reduction in renal function and occasionally end-stage renal disease. Risk factors for contrast-induced nephropathy (CN) are preexisting renal dysfunction, diabetes and reduced effective arterial volume. Hydration and use of nonionic contrast agents have been reported to ameliorate CN. Reactive oxygen species may have a role in the pathogenesis of CN. Statins decrease free oxygen radicals in animals. We retrospectively tested the hypothesis that administering statins prior to cardiac catheterization decreases the incidence of CN. METHODS: A total of 1,002 patients were studied. Patients with a stable baseline serum creatinine (SCr) > or = 1.5 mg/dl who had cardiac catheterization between July 1997 and June 2002, were included in the study. None of the patients were taking statins before admission. 250 patients were started on a statin before the procedure and 752 patients were not. The SCr was followed for 7 days after the procedure looking for an acute decrement in renal function, dialysis requirement and survival. RESULTS: The baseline characteristics, SCr, GFR, amount of intravenous fluids and contrast were similar in both groups. The post cath SCr (2.26 vs 3.1 mg/dl, p = 0.001) was significantly better in the statin group. Length of stay (2.72 vs 3.32 days, p = 0.01) and number of patients with acute renal failure (43 (17.2%) vs 168 (22.3%) patients, p = 0.028) were significantly lower in the statin group. Dialysis requirement within 7 days and 28-day survival were similar in both groups. CONCLUSION: Prophylactic administration of statins along with hydration may be associated with less CN induced by a nonionic, low-osmolality contrast.

Cardiac Catheterization↗
PubMed2002

Relating body condition to inorganic contaminant concentrations of diving ducks wintering in coastal California.

In wild waterfowl, poor winter body condition may negatively affect migration, survival, and reproduction. Environmental contaminants have been shown to adversely affect the body condition of captive birds, but few field studies have examined body condition and contaminants in wild birds during the winter. We assessed the body condition of carcasses from a collection of canvasbacks (Aythya valisineria) and lesser (A. affinis) and greater scaup (A. marila) wintering in coastal California. We used Akaike information criterion (AIC) to select the model with the best balance of parsimony and goodness of fit that related indices of body condition with concentrations of Cd, Cu, Hg, Se, and Zn. Total ash-free protein in canvasbacks decreased with increasing Se concentrations, and pancreas mass decreased with increasing Hg. We combined the closely related lesser and greater scaup in analyses and found that total carcass fat, pancreas mass, and carcass mass decreased with increasing Zn concentrations, and pancreas mass decreased with increasing Hg. Our AIC analysis indicated that some indices of body condition in diving ducks were inversely related to some environmental contaminants in this collection, but additional AIC analyses should be conducted across a wider range of contaminant concentrations to corroborate our findings.

Adipose Tissue↗
PubMed2002

Disseminated microsporidiosis in a renal transplant recipient.

Disseminated microsporidiosis is diagnosed uncommonly in patients not infected with human immunodeficiency virus (HIV). We present a case of disseminated microsporidiosis in a renal transplant recipient who was seronegative for HIV. Chromotrope-based stains were positive for microsporidia in urine, stools, sputum, and conjunctival scrapings. Electron microscopy, immunofluorescence, polymerase chain reaction, and cultures of renal tissue identified the organism as Encephalitozoon cuniculi. The patient was treated with oral albendazole and topical fumagillin with clinical improvement. In addition, she underwent a transplant nephrectomy and immunosuppressive therapy was withdrawn. Follow-up samples were negative for microsporidia. However, the patient developed central nervous system manifestations and died. An autopsy brain tissue specimen demonstrated E. cuniculi by immunofluorescent staining. Disseminated microsporidiosis must be considered in the differential diagnosis of multiorgan involvement in renal allograft recipients.

Animals↗
PubMed2001

Cyclic stretching of mesangial cells up-regulates intercellular adhesion molecule-1 and leukocyte adherence: a possible new mechanism for glomerulosclerosis.

Intraglomerular hypertension is a primary causal factor in the progressive glomerulosclerosis that characterizes diabetic nephropathy or severe renal ablation. However, inflammation of the glomerular mesangium also participates in at least the early phase of these diseases. In glomerulonephritis, where inflammation is thought to be the predominant causal factor, intraglomerular hypertension is also often present. Mesangial cells (MCs) are critical in orchestrating key functions of the glomerulus including extracellular matrix metabolism, cytokine production, and interaction with leukocytes. Because MCs are subject to increased stretching when intraglomerular hypertension is present, and in glomerulonephritis MC/leukocyte interactions seem to be mediated primarily via the up-regulation of intercellular adhesion molecule-1 (ICAM-1), we examine the possibility that cyclic stretching is a stimulus for increased MC ICAM-1 activity. We demonstrate that the normal low levels of MC ICAM-1 mRNA and protein are dramatically up-regulated by even short intervals of cyclic stretch. This effect is dose- and time-dependent, and requires little amplitude and a brief period of elongation for significant induction. Stretch-induced MC ICAM-1 also leads to a marked elevation in phagocytic leukocyte adherence. This stimulated adherence is equal or greater than that induced by the inflammatory cytokine tumor necrosis factor-alpha, whereas an additive effect occurs when both are applied in combination. Our results indicate that stretch-induced ICAM-1 may provide a direct link between hypertension and inflammation in the progression of injury and glomerulosclerosis in diabetes, renal ablation, and other forms of glomerulonephritis.

Animals↗
PubMed2001

Successful use of recombinant tissue plasminogen activator in a patient with relapsing peritonitis.

Intraperitoneal (IP) administration of either streptokinase (SK) or urokinase (UK) has assumed an adjunctive role to antibiotic therapy in selected patients with relapsing peritonitis. In these circumstances, bacteria may be protected from antibiotics through sequestration in either fibrinous structures or biofilms within the lumen of the peritoneal dialysis (PD) catheter or the peritoneal cavity. In some cases, it appears that disruption of these sheltered microenvironments by thrombolytic agents facilitated eradication of the offending organism and obviated the need for catheter removal, replacement, or interim hemodialysis. Although IP SK has been generally well tolerated as additive therapy in relapsing peritonitis, sporadic reports of significant complications, such as abdominal pain, fever, and severe hypotension, have precluded its more widespread acceptance. The only other thrombolytic agent used in this setting, UK, is presently unavailable because of a manufacturing shortfall. Therefore, adjunctive thrombolytic therapy for relapsing peritonitis is currently restricted. To circumvent these limitations, we devised an IP tissue plasminogen activator (tPA) protocol to eliminate recurring infection in a patient undergoing chronic ambulatory PD. After a third episode of peritonitis caused by Enterobacter cloacae, treated twice previously with an adequate antibiotic regimen, we instilled 6 mL of tPA (1 mg/mL) into the PD catheter for a 2-hour dwell time. The treatment was well tolerated and, in conjunction with a third course of antibiotic therapy, has produced an infection-free interval of 8 months.

Adult↗
PubMed2001

Determinants of mortality after myocardial infarction in patients with advanced renal dysfunction.

Previous studies using administrative data have shown high mortality in patients with renal failure requiring dialysis after acute myocardial infarction (AMI). There has been little investigation into the mortality after AMI in those with advanced renal disease who are not on dialysis therapy. We analyzed a prospective coronary care unit registry of 1,724 patients with ST segment elevation myocardial infarction admitted over an 8-year period at a single tertiary-care center. Those not on chronic dialysis therapy were stratified into groups based on corrected creatinine clearance, with cutoff values of 46.2, 63.1, and 81.5 mL/min/72 kg. Dialysis patients (n = 47) were considered as a fifth comparison group. Older age, black race, diabetes, hypertension, previous coronary disease, and heart failure were incrementally more common across increasing renal dysfunction strata. There were also graded increases in the relative risk for atrial and ventricular arrhythmias, heart block, asystole, development of pulmonary congestion, acute mitral regurgitation, and cardiogenic shock. Primary angioplasty, thrombolysis, and beta-blockers were used less often across the risk strata (P < 0.0001 for all trends). There was an early mortality hazard (age-adjusted relative risk, 8.76; P < 0.0001) for those with renal dysfunction but not on dialysis therapy for the first 60 months, followed by graded decrements in survival across increasing renal dysfunction strata. The excess mortality in this population appears to be mediated through arrhythmias, adverse hemodynamic events, and the lower use of mortality-reducing therapy.

Adult↗
PubMed2001

Comparison of patients' experiences during imaging tests of the colon.

BACKGROUND: Physical discomfort, anxiety, embarrassment, and other aspects of patient experience impact on future compliance for colonic imaging tests. Therefore, a prospective study was performed comparing patient experiences during air contrast barium enema (ACBE), flexible sigmoidoscopy, and colonoscopy. METHODS: Immediately after each procedure, patients completed a questionnaire assessing pretest anxiety, difficulty with preparation, pain, cramping, bloating, overall discomfort, loss of dignity, willingness to repeat the test, and overall satisfaction. A follow-up questionnaire was administered within 48 hours. Nurses and physicians also completed questionnaires to assess the provider impression of patient experience. RESULTS: Four hundred ten patients (80 ACBE, 202 sigmoidoscopy, 128 colonoscopy) were prospectively enrolled. Sigmoidoscopy caused more pain than ACBE (Odds ratio [OR] 2.64: 95% CI [1.63, 4.27]) or colonoscopy (OR 1.83: 95% CI [1.21, 2.77]). ACBE and colonoscopy did not differ in the degree of pain. Although overall satisfaction appeared to be similar for all tests, patients were less willing to repeat ACBE than sigmoidoscopy (OR 1.85: 95% CI [1.13, 3.02]) or colonoscopy (OR 1.82: 95% CI [1.07, 3.09]). Initial and follow-up pain ratings by patients were highly correlated (Spearman correlation 0.81); however, correlation of pain assessments between staff and patients was poor (Spearman correlation 0.48). CONCLUSIONS: Sigmoidoscopy was more painful than other colonic imaging modalities. Although ACBE and colonoscopy caused similar pain, patients were less willing to repeat ACBE. In aggregate, the data suggest that patients perceive colonoscopy as the most acceptable colonic imaging procedure. Better methods are required to allow staff to adequately assess discomfort experienced by patients during these procedures.

Adult↗
PubMed2001

Patient experience and preferences toward colon cancer screening: a comparison of virtual colonoscopy and conventional colonoscopy.

BACKGROUND: Virtual colonoscopy has excellent sensitivity for the detection of cancer and polyps greater than 1 cm in diameter. For virtual colonoscopy to succeed as a screening test for colorectal neoplasia, it must be well tolerated and accepted by patients. Patients' experiences with virtual colonoscopy and conventional colonoscopy were assessed and compared. METHODS: Patients referred to the GI clinic for colonoscopy for any indication were recruited to undergo virtual colonoscopy before conventional colonoscopy. Patients were asked to complete a questionnaire twice: after virtual colonoscopy and after completing both tests. Three variables, overall pain, discomfort, and lack of respect, were assessed by using a 7-point Liken scale with higher scores denoting a worse experience. Patients' preferences for virtual colonoscopy versus conventional colonoscopy were determined with a time tradeoff technique. To verify response stability, patients were asked to return an additional questionnaire by mail at 24 hours. RESULTS: Two hundred ninety-five patients completed the questionnaire immediately after the procedures, and 83 patients completed the questionnaire at 24 hours. At both 0 and 24 hours, patients reported more pain, discomfort, and less respect after virtual colonoscopy than conventional colonoscopy (p < 0.01). The overall agreement (Kappa statistic) between times 0 and 24 hours was fair. Patients reported that they preferred conventional colonoscopy and would wait longer for conventional colonoscopy (mean = 4.9 weeks) than undergo a virtual colonoscopy (p < 0.01). CONCLUSIONS: Patients tolerate both virtual colonoscopy and conventional colonoscopy, although they report more pain, discomfort, and less respect undergoing virtual colonoscopy. Efforts to improve patient experience during virtual colonoscopy need to be investigated.

Abdominal Pain↗
PubMed2001

A statistical 3-D pattern processing method for computer-aided detection of polyps in CT colonography.

Adenomatous polyps in the colon are believed to be the precursor to colorectal carcinoma, the second leading cause of cancer deaths in United States. In this paper, we propose a new method for computer-aided detection of polyps in computed tomography (CT) colonography (virtual colonoscopy), a technique in which polyps are imaged along the wall of the air-inflated, cleansed colon with X-ray CT. Initial work with computer aided detection has shown high sensitivity, but at a cost of too many false positives. We present a statistical approach that uses support vector machines to distinguish the differentiating characteristics of polyps and healthy tissue, and uses this information for the classification of the new cases. One of the main contributions of the paper is the new three-dimensional pattern processing approach, called random orthogonal shape sections method, which combines the information from many random images to generate reliable signatures of shape. The input to the proposed system is a collection of volume data from candidate polyps obtained by a high-sensitivity, low-specificity system that we developed previously. The results of our ten-fold cross-validation experiments show that, on the average, the system increases the specificity from 0.19 (0.35) to 0.69 (0.74) at a sensitivity level of 1.0 (0.95).

Adult↗
PubMed2001

Colorectal neoplasia: performance characteristics of CT colonography for detection in 300 patients.

PURPOSE: To determine the sensitivity and specificity of computed tomographic (CT) colonography for colorectal polyp and cancer detection by using colonoscopy as the reference standard. MATERIALS AND METHODS: Three hundred patients underwent CT colonography followed by standard colonoscopy. Bowel preparation consisted of magnesium citrate and polyethylene glycol. After colonic air insufflation, patients underwent scanning in the supine and prone positions with 3-mm collimation during a single breath hold. The transverse CT images, sagittal and coronal reformations, and three-dimensional endoluminal images were interpreted by two radiologists independently, and then a consensus reading was performed. CT colonographic findings were correlated with standard colonoscopic and histologic findings. RESULTS: The overall sensitivity and specificity of CT colonography for polyp detection were 90.1% (164 of 182) and 72.0% (85 of 118), respectively. By using direct polyp matching, the overall sensitivity was 69.7% (365 of 524). The sensitivity was 90% (74 of 82) for the detection of polyps 10 mm or larger, 80.1% (113 of 141) for polyps 5.0-9.9 mm, and 59.1% (178 of 301) for polyps smaller than 5 mm. The sensitivity was 94% (64 of 68) for the detection of adenomas 10 mm or larger, 82% (72 of 88) for adenomas 5.0-9.9 mm, and 66.9% (95 of 142) for adenomas smaller than 5 mm. CT colonography was used to identify all eight carcinomas. CONCLUSION: CT colonography has excellent sensitivity for the detection of clinically important colorectal polyps and cancer.

Adenomatous Polyps↗
PubMed2001

Analysis of initial CT findings after endovascular repair of abdominal aortic aneurysm.

PURPOSE: To determine the spectrum and frequency of specific computed tomographic (CT) findings in the acute period after endovascular repair of abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: CT images obtained 1--3 days after endograft placement were evaluated in 88 patients. The images were analyzed for stent position, appearance of endograft components, perigraft leak, and postoperative findings including air and acute thrombus within the aneurysm and air surrounding the femoral-femoral bypass graft. Findings that could be misinterpreted as perigraft leak were evaluated. RESULTS: Fifteen (17%) of 88 patients had perigraft leak in the acute postoperative period. The bare segment of the proximal self-expanding stent covered one or both renal arteries in 54 (61%) patients. One patient had CT evidence of renovascular compromise. Postoperative air was within the aneurysmal sac in 51 (58%) patients and surrounded the femoral-femoral bypass graft in 67 (94%) of 71 patients in whom the grafts were evaluated with CT. Mottled attenuation within the aneurysmal sac was seen in 50 (57%) patients. Forty-six (52%) patients had calcifications within longstanding thrombus. In 31 (35%) patients, findings that could have been misinterpreted as perigraft leak were identified. CONCLUSION: Accurate analysis of CT findings after endovascular AAA repair requires careful review of all available CT images (preprocedural and pre- and postcontrast) and clear understanding of specific stent-graft components and placement.

Aged↗
PubMed2000

Experimental infection model for Sin Nombre hantavirus in the deer mouse (Peromyscus maniculatus).

The relationship between hantaviruses and their reservoir hosts is not well understood. We successfully passaged a mouse-adapted strain of Sin Nombre virus from deer mice (Peromyscus maniculatus) by i.m. inoculation of 4- to 6-wk-old deer mouse pups. After inoculation with 5 ID(50), antibodies to the nucleocapsid (N) antigen first became detectable at 14 d whereas neutralizing antibodies were detectable by 7 d. Viral N antigen first began to appear in heart, lung, liver, spleen, and/or kidney by 7 d, whereas viral RNA was present in those tissues as well as in thymus, salivary gland, intestine, white fat, and brown fat. By 14 d nearly all tissues examined displayed both viral RNA and N antigen. We noted no consistent histopathologic changes associated with infection, even when RNA load was high. Viral RNA titers peaked on 21 d in most tissues, then began to decline by 28 d. Infection persisted for at least 90 d. The RNA titers were highest in heart, lung, and brown fat. Deer mice can be experimentally infected with Sin Nombre virus, which now allows provocative examination of the virus-host relationship. The prominent involvement of heart, lung, and brown fat suggests that these sites may be important tissues for early virus replication or for maintenance of the virus in nature.

Animals↗
PubMed2000

Targeting of N-CoR and histone deacetylase 3 by the oncoprotein v-erbA yields a chromatin infrastructure-dependent transcriptional repression pathway.

Transcriptional repression by nuclear hormone receptors is thought to result from a unison of targeting chromatin modification and disabling the basal transcriptional machinery. We used Xenopus oocytes to compare silencing effected by the thyroid hormone receptor (TR) and its mutated version, the oncoprotein v-ErbA, on partly and fully chromatinized TR-responsive templates in vivo. Repression by v-ErbA was not as efficient as that mediated by TR, was significantly more sensitive to histone deacetylase (HDAC) inhibitor treatment and, unlike TR, v-ErbA required mature chromatin to effect repression. We find that both v-ErbA and TR can recruit the corepressor N-CoR, but, in contrast to existing models, show a concomitant enrichment for HDAC3 that occurs without an association with Sin3, HDAC1/RPD3, Mi-2 or HDAC5. We propose a requirement for chromatin infrastructure in N-CoR/HDAC3-effected repression and suggest that the inability of v-ErbA to silence on partly chromatinized templates may stem from its impaired capacity to interfere with basal transcriptional machinery function. In support of this notion, we find v-ErbA to be less competent than TR for binding to TFIIB in vitro and in vivo.

Adenosine Triphosphatases↗
PubMed2000

Diagnostic dilemma

In those issues in which our regular Case of the Month does not appear, The Green Journal will present a Diagnostic Dilemma-an electrocardiogram and/or radiograph with a brief case history-for our readers to solve. The correct answer appears on p. 511 of this issue.If you would like to contribute a Diagnostic Dilemma, please submit a high-quality copy of the EKG or radiograph with a brief synopsis (<250 words) of the case to The American Journal of Medicine's editorial office.

Journal Article↗