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Biomedical subjects

Robert Siegel

Publications and source records attributed to Robert Siegel.

10 recordsLinked to original sources
PubMed2005

Use of the nuclease inhibitor aurintricarboxylic acid (ATA) for improved non-viral intratumoral in vivo gene transfer by jet-injection.

BACKGROUND: Stability, integrity and retention of the DNA within the targeted tissue is decisive for efficient gene transfer using naked DNA. Pre-clinical and clinical studies require reproducible transfection rates by preventing rapid degradation of naked DNA in the transduced tissue. Tumor tissues contain nuclease activity, which can affect DNA stability if naked DNA is used. Therefore, inhibition of nuclease-mediated DNA degradation by the nuclease inhibitor aurintricarboxylic acid (ATA) might lead to improved gene transfer efficiency in tumor tissues. METHODS: For both, DNA-degradation analysis and in vivo gene transfer experiments, the beta-galactosidase (LacZ)-expressing pCMVbeta and the cytosine deaminase (CD)-expressing pCMV-CD plasmid were used. Influence of the nuclease inhibitor ATA was determined in tumors, in which naked pCMVbeta or pCMV-CD DNA and ATA was co-administered by jet-injection. The nuclease activity and inhibition by ATA was analyzed using the DNase Alert detection system. The influence of ATA on LacZ expression was determined by specific ELISA and its effect on the therapeutic efficacy of CD gene transfer on tumor growth was determined in vivo. RESULTS: The screening of different human mammary and colon carcinoma models revealed strong nuclease activity rapidly degrading naked plasmid DNA. Co-administration of ATA with pCMVbeta or pCMV-CD for in vivo jet-injection of tumors prevented DNA from nuclease degradation associated with either increased LacZ gene expression or improved reduction in tumor growth. CONCLUSIONS: Tumor-associated nuclease activity is a notable hurdle in gene transfer of naked DNA and therefore inhibition of nucleolytic degradation of plasmid DNA facilitates intratumoral gene expression.

Aurintricarboxylic Acid↗
PubMed2005

Physician knowledge and management of children exposed to domestic violence in Ohio: a comparison of pediatricians and family physicians.

Active members of the Ohio chapters of American Academy of Family Physicians (FP=1,498) and American Academy of Pediatrics (Ped=1,725) were surveyed about their knowledge and management regarding children exposed to domestic violence (DV). Characteristics of respondents were analyzed by use of Chi-square analysis. Logistic regression was performed to identify predictors of DV knowledge and management. The response rate was 33.3%. Family physicians were more likely to know their local DV agency and recognize the adult symptoms of DV, such as unexplained injury. Pediatricians were more likely to report the child who saw a fight between parents to child protective services. Continuing work to increase physicians' comfort and ability to assess for DV and manage exposed children is needed.

Adult↗
PubMed2004

Flow cytometric screening of yeast surface display libraries.

A method to screen and isolate antigen specific clones from a library of single-chain antibodies expressed on the surface of yeast cells is presented. Two rounds of magnetic bead enrichment before flow cytometric sorting enables one to screen libraries of far greater diversity than can be screened by just flow cytometry. The strength of flow cytometric sorting is the ability to follow the selection in real time and to isolate easily the highest affinity antigen-specific clones. A major strength of yeast display as a discovery platform is the ability to characterize the binding properties, the affinity of a clone without the need for subcloning, expression, and purification of the scFv. The methodology for directed evolution of single-chain antibodies to increase the affinity of a clone is also described.

Agar↗
PubMed2003

Safety of an aspirin-alone regimen after intracoronary stenting with a heparin-coated stent: final results of the HOPE (HEPACOAT and an Antithrombotic Regimen of Aspirin Alone) study.

BACKGROUND: Stent thrombosis is an infrequent complication of intracoronary stenting that often has devastating clinical consequences. This study assesses the additional benefit of heparin coating with the BX VELOCITY Balloon-Expandable Stent with HEPACOAT, Carmeda end-point attached heparin (HEPACOAT) in patients with de novo or restenotic native coronary artery lesions treated with aspirin monotherapy after optimal stenting. METHODS AND RESULTS: This was a multicenter, prospective, nonrandomized, pilot study. Two hundred patients (69% men; mean age, 64.1+/-11.2 years) meeting the eligibility criteria were treated with the HEPACOAT stent and aspirin alone after stenting. Any other antiplatelet or anticoagulation therapy was not permitted. Procedural success was achieved in all patients. There were 3 postprocedural non-Q-wave myocardial infarctions. The primary end point of stent thrombosis at 30 days occurred in 2 of 200 patients (1%): in one after blunt chest trauma and in the other in the setting of essential thrombocytosis. Major adverse cardiac events (death, myocardial infarction, target lesion revascularization, and coronary artery bypass grafting) were observed at 30 days in 5 of 200 (2.5%) patients. CONCLUSIONS: The BX VELOCITY stent with HEPACOAT and aspirin alone after the procedure was safe in select patients with de novo or restenotic lesions in native coronary arteries. Heparin coating provides additional protection against stent thrombosis.

Angioplasty, Balloon, Coronary↗
PubMed2003

Comparison of usefulness of dipyridamole stress myocardial contrast echocardiography to technetium-99m sestamibi single-photon emission computed tomography for detection of coronary artery disease (PB127 Multicenter Phase 2 Trial results).

We hypothesized that assessment of hyperemic myocardial blood flow (MBF) velocity using myocardial contrast echocardiography (MCE) can detect coronary artery disease (CAD). We also postulated that only a single MCE study during stress is required for the detection of CAD in patients with normal function at rest. Patients with known or suspected CAD referred for dipyridamole stress technetium-99m sestamibi single-photon emission computed tomographic (SPECT) studies were enrolled. MCE was performed concurrently with SPECT using continuous infusions of PB127 during intermittent harmonic power Doppler imaging at multiple pulsing intervals. MCE and SPECT were compared in 43 of 54 patients who had adequate studies using both techniques. In 15 of the 43 patients, coronary angiography was performed within 30 days of the MCE/SPECT tests. Overall concordance for classification of patients as normal versus abnormal was 84% (kappa = 0.63) between the 2 tests. When false-negative SPECT scans were corrected for results of angiography, concordance increased to 93% (kappa = 0.82). For territorial analysis, concordance between MCE and SPECT for location of perfusion defects was 65% (kappa = 0.41) and 74% (kappa = 0.61) after SPECT was corrected by angiography. In patients with normal function at rest, a single stress MCE perfusion study allowed identification of CAD with the same concordance as rest/stress perfusion studies. In conclusion, visual assessment of regional differences in MBF velocity using PB127 allows detection of CAD with good concordance compared with technetium-99m sestamibi SPECT. In patients with normal left ventricular function at rest, a single stress PB127 MCE perfusion study is adequate for the detection of CAD.

Adult↗
PubMed2003

Antibodies in proteomics I: generating antibodies.

The explosion in genome sequencing, and in subsequent DNA array experiments, has provided extensive information on gene sequence, organization and expression. This has resulted in a desire to perform similarly broad experiments on all the proteins encoded by a genome. Panels of specific antibodies, or other binding ligands, will be essential tools in this endeavour. Because traditional immunization will be unlikely to generate antibodies in sufficient quantity, and of the required quality and reproducibility, in vitro selection methods will probably be used. This review--the first of two--examines the strategies available for in vitro antibody selection. The second review discusses the adaptation of these methods to high throughput and the uses to which antibodies, once derived, can be put.

Animals↗
PubMed2003

Antibodies in proteomics II: screening, high-throughput characterization and downstream applications.

There are many ways in which the use of antibodies and antibody selection can be improved and developed for high-throughput characterization. Standard protocols, such as immunoprecipitation, western blotting and immunofluorescence, can be used with antibody fragments generated by display technologies. Together with novel approaches, such as antibody chips and intracellular immunization, these methods will yield useful proteomic data following adaptation of the protocols for increased reliability and robustness. To date, most work has focused on the use of standard, well-characterized commercial antibodies. Such protocols need to be adapted for broader use, for example, with antibody fragments or other binders generated by display technologies, because it is unlikely that traditional approaches will provide the required throughput.

Antibodies↗
PubMed2003

Myocardial contrast echocardiography (MCE) with triggered ultrasound does not cause premature ventricular complexes: evidence from PB127 MCE studies.

Previous studies suggest that myocardial contrast echocardiography using high mechanical index triggered ultrasound can be associated with increased frequency of the premature ventricular complex (PVC). However, this association has not been systematically examined. PB127 (Point Biomedical Corp, San Carlos, Calif) is a novel microsphere designed for evaluation of myocardial perfusion with ultrasound. PB127 myocardial contrast echocardiography was performed with triggered harmonic power Doppler in early/mid diastole (mechanical index </= 1.0). A total of 71 patients (cohort A) were studied at rest and another 64 (cohort B, age 62 +/- 12.6 years) were allocated to stress. Continuous electrocardigraphy was recorded. The study evaluated premature ventricular complex frequency at baseline, during, and after infusion of PB127 (dose < 0.175 mg/kg, <60-minute duration). Proportions of triggered and nontriggered intervals associated with premature ventricular complex were determined. PVC frequency did not increase with PB127 infusion in either cohort (P =.572, P =.263). Proportion of triggered intervals after QRS associated with PVC was similar to proportion of untriggered intervals in cohort A (P >.999) and was lower than untriggered intervals (P =.001) in B, suggesting that triggers do not cause PVC. PB127 does not cause increase PVC frequency during or after imaging with triggered ultrasound at mechanical index of 1.

Adult↗
PubMed1993

Triage practice guideline for patients hospitalized with congestive heart failure: improving the effectiveness of the coronary care unit.

BACKGROUND: Decisions regarding the appropriate timing for transfer of patients hospitalized with congestive heart failure from the coronary care unit (CCU) to the medical ward are often not based on well-founded medical data. We investigated the potential safety and effectiveness of a practice guideline recommending early "step-down" transfer of low-risk patients with congestive heart failure. PATIENTS AND METHODS: We studied the use of a practice guideline for 384 patients hospitalized with congestive heart failure in a hypothetic experiment. The guideline stated that patients without any of the following conditions may be suitable for transfer to a nonmonitored bed 24 hours after admission: acute myocardial infarction or ischemia, complications, active or planned cardiac interventions, unstable comorbidity, worsening clinical status, or lack of response to diuretic therapy. Patients with any of the above conditions were classified as higher risk and potentially not suitable for early transfer. RESULTS: Life-threatening complications were 15.2 times more likely (95% confidence interval [CI] 2.2, 70, p = 0.001) and death 14.6 times more likely (95% CI 2.1, 68, p = 0.001) if the patient was classified as "high risk" rather than "low risk" by the guideline. The negative predictive value and sensitivity of the practice guideline for detecting patients who had life-threatening complications were 99.2% and 96.4%, respectively. Thirty-one percent of patients with congestive heart failure hospitalized in either the CCU or intermediate care unit were at low risk and potentially suitable for transfer to a nonmonitored bed 24 hours after admission. Use of the guideline would have reduced intermediate care unit lengths of stay from 2.91 days to 2.22 days and CCU length of stay from 2.06 to 2.04 days had it been used to triage patients with congestive heart failure. This reduction in length of stay would have resulted in 172 more intermediate care unit bed-days available per year to accommodate additional patients. On initial review, at least one cardiologist reviewer judged that use of the guideline may have adversely affected quality of care for 4% (95% CI 1%, 7%) of patients. After a consensus among the cardiologist reviewers, it was judged that the guideline may have adversely affected care for only 0.8% of patients (95% CI, 0%, 2.3%), and that no patient (95% CI 0%, 2.3%) would have had an unexpected life-threatening complication because of the guideline. CONCLUSIONS: Use of a practice guideline has the potential to reduce the intermediate care unit lengths of stay for selected low-risk patients with congestive heart failure.

Aged↗