Ralph S Greco

Stanford University, Palo Alto, CA, USA

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Publications (5)43.2 Total impact

  • Article: Symbiotic or Parasitic? A Review of the Literature on the Impact of Fellowships on Surgical Residents.
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    ABSTRACT: OBJECTIVE:: We conducted a systematic review of published literature to gain a better understanding of the impact of advanced fellowships on surgical resident training and education. BACKGROUND:: As fellowship opportunities rise, resident training may be adversely impacted. METHODS:: PubMed, MEDLINE, Scopus, BIOSIS, Web of Science, and a manual search of article bibliographies. Of the 139 citations identified through the initial electronic search and screened for possible inclusion, 23 articles were retained and accepted for this review. Data were extracted regarding surgical specialty, methodology, sample population, outcomes measured, and results. RESULTS:: Eight studies retrospectively compared the eras before and after the introduction of a fellowship or trended data over time. Approximately half used data from a single institution, whereas the other half used some form of national data or survey. Only 3 studies used national case data. Fourteen studies looked at general surgery, 6 at obstetrics-gynecology, 2 at urology, and 1 at otolaryngology. Only one study concluded that fellowships have a generally positive impact on resident education, whereas 9 others found a negative impact. The remaining 13 studies found mixed results (n = 6) or minimal to no impact (n = 7). CONCLUSIONS:: The overall impact of advanced surgical fellowships on surgical resident education and training remains unclear, as most studies rely on limited data of questionable generalizability. A careful study of the national database of surgery resident case logs is essential to better understand how early surgical specialization and fellowships will impact the future of general surgery education.
    Annals of surgery 09/2012; · 7.90 Impact Factor
  • Article: Bilateral adrenal medullary hyperplasia associated with an SDHB mutation.
    Journal of Clinical Oncology 01/2011; 29(8):e200-2. · 18.37 Impact Factor
  • Article: Fabrication of multi-layered biodegradable drug delivery device based on micro-structuring of PLGA polymers.
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    ABSTRACT: A programmable and biodegradable drug delivery device is desirable when a drug needs to be administered locally. While most local drug delivery devices made of biodegradable polymers relied on the degradation of the polymers, the degradation-based release control is often limited by the property of the polymers. Thus, we propose micro-geometry as an alternative measure of controlling drug release. The proposed devices consist of three functional layers: diffusion control layer via micro-orifices, diffusion layer, and drug reservoir layers. A micro-fabrication technology was used to shape an array of micro-orifices and micro-cavities in 85/15PLGA layers. A thin layer of fast degrading 50/50PLGA was placed as the diffusion layer between the 85/15PLGA layers to prevent any burst-type release. To modulate the release of the devices, the dimension and location of the micro-orifices were varied and the responding in vitro release response of tetracycline was monitored over 2 weeks. The release response to the different micro-geometry was prominent and further analyzed by FEM simulation. Comparison of the experiments to the simulated results identified that the variation of micro-geometry influenced also the volume-dependent degradation rate and induced the osmotic pressure.
    Biomedical Microdevices 01/2008; 9(6):845-53. · 3.03 Impact Factor
  • Article: The construction of three-dimensional micro-fluidic scaffolds of biodegradable polymers by solvent vapor based bonding of micro-molded layers.
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    ABSTRACT: It is increasingly important to control cell growth into and within artificial scaffolds. Tissues such as skin, blood vessels, and cartilage have multi-layer structures with different cells in each layer. With the aid of micro-fabrication technology, a novel scaffolding method for biodegradable polymers such as polylactic acid (PLA), polyglycolic acid (PGA), and the copolymers poly(lactide-co-glycolide)(PLGA), was developed to construct three-dimensional multi-layer micro-fluidic tissue scaffolds. The method emphasizes micro-fluidic interconnections between layers within the scaffolds and maintenance of high-resolution geometries during the bonding process for the creation of multi-layered scaffolds. Micro-holes (10-100 microm), micro-channels, and micro-cavities were all created by micro-molding. Solvent-vapor based bonding of micro-molded layers preserved 20 microm sized structures. Sample scaffolds were constructed for purposes such as channel-directed cell growth and size-based cell sorting. Further extension of these techniques to create a micro-vascular network within or between layers is possible. Culturing of human coronary artery endothelial cells (HCAECs) on the sample scaffolds demonstrated the biocompatibility of the developed process and the strong influence of high-resolution micro-geometries on HCAEC growth.
    Biomaterials 03/2007; 28(6):1174-84. · 7.40 Impact Factor
  • Article: Immunohistochemical profile of the sodium/iodide symporter in thyroid, breast, and other carcinomas using high density tissue microarrays and conventional sections.
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    ABSTRACT: Extrathyroidal cancers could potentially be targeted with (131)I, if the Na(+)/I(-) symporter (NIS) were functional. Using immunohistochemical methods we probed 1278 human samples with anti-NIS antibody, including 253 thyroid and 169 breast conventional whole tissue sections (CWTS). Four high density tissue microarrays containing a wide variety of breast lesions, normal tissues, and carcinoma cores were tested. The results of the normal microarray were corroborated in 50 CWTS. Nineteen of 34 normal tissues, including bladder, colon, endometrium, kidney, prostate, and pancreas, expressed NIS. Nineteen of 25 carcinomas demonstrated NIS immunopositivity; 55.7% of 479 carcinoma microarray cores expressed NIS, including prostate (74%), ovary (73%), lung (65%), colon (62.6%), and endometrium (56%). NIS protein was present in 75% benign thyroid lesions, 73% thyroid cancers, 30% normal-appearing, peritumoral breasts, 88% ductal carcinomas in situ, and 76% invasive breast carcinoma CWTS. Comparatively, breast microarray cores had lower immunoreactivity. Plasma membrane immunopositivity was confirmed in thyrocytes, salivary ductal, gastric mucosa, and lactating mammary cells. In other tissues, immunoreactivity was predominantly intracellular, particularly in malignant lesions. Thus, NIS is present in many normal epithelial tissues and is predominantly expressed intracellularly in many carcinomas. Elucidating the regulatory mechanisms that render NIS functional in extrathyroidal carcinomas may make (131)I therapy feasible.
    Journal of Clinical Endocrinology &amp Metabolism 05/2003; 88(4):1880-8. · 6.50 Impact Factor